I just swapped ROTT for The Witcher 3 Game Of The Year edition which came with Hearts of Stone and Blood and Wine. What I want to know is can you access both DLCs from the main game or do you have to launch them separately from the start up menu? I'm really hoping I can just stumble across them in the main game so all three games form a cohesive whole.

Yes, you'll stumble across the DLC during your game. The level requirements are pretty high, so you'll likely do those towards the end of your adventure though.

So both DLCs will eventually turn up on the quests boards?

Yes. They're already part of the main game. You dont have to install them separately.

Yes.

The game will let you know when a certain mission is part of the DLC, there's a Blood & Wine or Hearts of Stone icon next to it. You'll know it when you see it. Other than that, it blends perfectly into the game. If the icon wasn't there, I couldn't tell what part was from the DLC or what quests were part of the main game.

Great news! Is there any particular order to best tackle the DLC? I won't be taking them on until I'm at least level 30 but from my understanding Hearts Of Stone is a follow on from the main story, so I'd expect that to appear after I finish the main quest, and Blood and Wine is a separate story, so I'd expect to be able to pick that up at my leisure when my level is sufficiently high. Is that correct?

The blood and wine one will appear on a quest board after a certain mission is done (roughly half way through the game)

Hearts of stone should appear as a main quest by its one. Just open the main mission quests, and you should see it. It's marked in blue. Both are part of the game and you don't need to access them from the main menu. You can play them with a default character they set for you, if you already played the main game and don't have your saved character for some reason 

Thanks everyone, I'm really looking forward to taking my time and enjoying this mammoth version of TW3.

I'm a massive TW3 fan. I finished the main story twice, and I am currently playing blood and wine, and then will get to hearts of stone. I had trouble with the DLC and regions so I had to wait until I got it resolved. If you ever want any help let me know. I'd gladly offer it. Always great to talk about the true GOTG

I know very little about the expansion packs. Am I right in thinking Hearts Of Stone takes place on the same map as the main quest and Blood and Wine takes place on a completely new map?