For England, I'm trying to decide if it's better to avoid taking land and rushing tech for QftNW, or take lands from Scotland and get the idea later. And suggestions?
EDIT: Welp! Seems paradox decided to make it a pain in the ass to colonize the new world as England and England is closer to the New world than Greenland. Almost prepared to go back to EU3 with how much they are messing with the AI and historical accuracy for the sake of multiplayer balance that will never be achieved.
England (that owns Ireland) needs dip tech 8 plus exploration ideas to start colonising the new world. You can also steal colonises from the Iberian scum if you want to slingshot into colonisation earlier. This is due to a concept called "trade winds" which lower the distance and travel speeds in a single direction of certain ocean provinces (use your trade map to see them).
While I don't think I've ever played England I have played a couple of Irish games and I find if you want to play the colony game from the British Isles it's best to just skip Exploration as a first idea unless you want to cheese it by stealing colonies or declaring on weak minors in Iberia/NA.
Personally I would likely pick up something like diplomatic first so you can play the majors in Europe against each other and to potentially help diplo-vassalise small revolter states. Humanism or military are another possibility if you fear the bad revolts.
You can leave the Scots and Celts to annex later or aggressively assualt them early, either way they're never going to be a major threat outside of the lollard revolt/war of the roses. I would mainly keep an eye on the lowlands and try to steal some provinces from Burgundy before the succession crisis happens.
I would ideally aim for a non-dutch tag and release it as a march and try to feed it as much as possible. This will allow you to have a presence in Europe (without losing your island advantage), have a target to both distract/attack France from and finally you can integrate it later in the game when you want to get the complete share of the English Channel trade node.
Colonisation should be a side-game in EU4 for most Europeans until you start scrambling for Asia later. Even then consider most colonising will be done by the Iberians and will be trivial to take later in the game.