On the listing it says rechargeable battery pack but battery pack normally means removable and the Switch has pretty much confirmed as having a non-replaceable battery.
This could be a bundle price, maybe the premium version with a few extras forcibly added because they have limited stock allocation and are expecting it sell well.
I think the basic pack has been pretty much confirmed to be £199 as there is a company taking pre-orders with a guaranteed price of £198.50.