Ok. 

I know a lot of people consider the U.K. to be 1 of Nintendo's weakest markets. Not sure where some get that perception from. Maybe some are native? Or get the idea from looking at raw sales figures? Or word of mouth? Or even from general perception? As a U.K. resident i can certainly say they have a point, at least somewhat. 

I wouldn't say it's a massively bad market for Nintendo but given it's probably the 3rd biggest single videogames market there is certainly room for improvement. It's nowhere near Nintendo's biggest market but certainly not their worst. The following evidence i am about to give is somewhere between anecdotal and fact.

as a U.K. resident i can confirm that Nintendo's store presence is absolutely pathetic in the U.K. To buy software for it, your best bet would be to visit GAME, a specialist games store. Nintendo has limited impact space there. Most GAME stores i see are pretty much dominated by PS4/Xboxone products. Nintendo products are usually tucked away somewhere with about as much space dedicated to them as last gen Ps/Xbox. The last time i personally remember seeing a Nintendo product having as much shelf space as Ps/Xbox was probably roughly halfway through the Wii era. Ever since then, floorspace dedicated to Nintendo has gradually shrunk.

The biggest Supermarket in the U.K., Tesco, mostly doesn't sell Nintendo products AT ALL, apart from a few of the larger hyperstores. It has been this way since the early days of Wii u. After 2-3 years on the market Tesco quietly dropped it. The 2nd biggest supermarket, Sainsbury is in a similar situation. Very few stores have dedicated Nintendo sections. I believe their online store has dropped Nintendo completely. The 3rd biggest supermarket, Asda, again has dropped Nintendo products since the early days of Wii u COMPLETELY! These stores all have decent sized sections dedicated to Ps4 and Xboxone and most EVEN have some space dedicated to last gen ps/xbox products! I first began noticing this about 2 years ago and at the time i definitely raised an eyebrow, considering the 3ds was at the time selling comparably to Xboxone/Ps4 but all 3ds products were being dropped from stores, whilst they were retaining Ps3/Xbox360 sections! I think Nintendo needs a lot more presence in U.K. stores. They either need new sales reps big-time, or these stores are taking "backhanders".  Of these stores only Tesco sells switch/3ds and related products online.

The biggest problem i see for Nintendo is that just about every store which sells gaming products, both instore and online ONLY sell 1st party and major 3rd party releases. Smaller 3rd party products are barely sold at retail AT ALL! This was confirmed to me whilst searching info for buying redout online. It was on sale online in just ONE place! A specialist online games store. This was the only place i could find it for sale online or instore and it took quite a lot of searching.

So, in conclusion. Nintendo needs a far bigger presence instore, decent reps who can guarantee at least decent shelf space everywhere. There is actually a little bit of buzz about the switch here but this time my evidence is anecdotal. That said,i feel Nintendo has done a good job of marketing/advertising the Switch here. I've seen lots of commercials here for it, both at peak time and on the major T.V. channels. Most people seem to be at least aware of what the Switch is. The biggest problem i can see here is the SW, particularly the 3rd party and particularly the smaller 3rd party Sw. It really will sell rather badly if only 1 outlet in the whole country is selling it! Nintendo also need to try and work with 3rd parties, so that ALL SW is given shelf space, even casual browsers can see it. If this can't be rectified then some 3rd party sales are going to be abysmal in the U.K. Even if Switch HW sales are good, Nintendo still needs even the smaller 3rd party titles to sell well. Apart from that, the U.K. gaming public will likely miss a few gems too

SOURCE:- My 2 eyes

Well i still think retail gaming is pretty important, both from Nintendo and third parties' perspectives. The really important thing to take from this was my own personal experiences trying to find redout though.

Maybe it's Nintendo who hates the UK?

All the tescos around my way sell nintendo. Also the reason nintendo doesn't sell well in uk is cos it's seen as kiddy. Simple as that.

Too many average gamers.

I already looked at the numbers, seemingly UK doesn't hate so much Nintendo, as they love MS: http://gamrconnect.vgchartz.com/post.php?id=8406634

OP is ignoring the cultural factor here. Regardless of store presence, I doubt that Nintendo could ever be very popular in Britain.

Nintendo has carved a niche as the family-friendly console maker and most of itsbig franchises have a cute and cartoonish feel to them. If you look at the games that sell in Britain, they're all either very realistic simulation games like FIFA or Gran Turismo, or they're games with a gritty and "mature" aesthetic. Games with a cuter or more whimsical style just don't sell here (one of the things that makes Persona 5's sales in Britain so shocking is that this is an incredibly hard territory for animé-style game).

This based on purely anecdotal evidence, but I always get the impression that British children are expected to "grow out" of cartoons and other child-friendly things at a younger age when compared to American kids, and that the stigma of liking things aimed at children is stronger here too. I remember back in primary school, it was pretty much universally agreed by 8-year-olds that Nintendo was "for kids" and that this was definitely a bad thing. This was a while ago, but I don't get the impression that much has changed since then, and I see the same attitudes from my younger cousins.

We all know that Nintendo de-cutified a lot of its Japanese boxart in the 90s and early 00s in order to appeal to the American audience:

I think they need to do the same thing to an even greater degree if they want to be successful in Britain. Maybe they'd be one of the bigger manufacturers here if Link looked like this:

UK loves Nintendo products if its a sub £200 portable system but not so much home consoles. I have a huge Tesco store and did see 2 Switch games on a bottom shelf hidden away. One Game store I looked in recently does have a better Switch section now, close to the front of the shop (good sign) but no demo Switch console. It's why I think going beyond Nintendo enthusiasts may be difficult in the UK because it has little presence to remind people it exists. In fairness a lot of retailers made losses with the wii u and it left a sour taste I'm sure but I think if the Switch does have momentum and online sales are strong then the high street presence will improve.

As previously stated though UK is a strong market for Microsoft.

I think even if the UK slows down much faster than the rest of the world with regard sales I think it will pick up nicely again when the Switch goes sub £200 in a year or so. It's almost like a barrier in parent's minds that they won't spend £200+ on a handheld console for their kids.

I think the new 2DS will do brilliantly well in the UK at Christmas with likely 3ds/2ds models outselling the Switch if Switch remains at the £280 price point. Last year 3DS had 7% of the market in the UK for hardware with many parents often replacing damaged units with new in addition to new owners. The new 2DS pricing will be great for them. Despite our love of the ps4 the outgoing premium portable format Vita has a tiny market share of 0.4%.

http://www.neogaf.com/forum/showthread.php?t=1332976

You could have a point. Only during Wii days have i seen Nintendo even make an effort here. I feel they could do so much more to at least have a better physical presence in stores. I don't think they even have their own reps. Pretty sure they use a 3rd party.