I took diplomatic as first Idea Group => Reason: To colonize effectively as non Portugal/Castille, the first Ideagroup is too early. Additionally, if you complete the group, you have instantly -24% Tech cost for diplomatic tech, for the Rest of the game! Then, as I always have a lot of alliances (right now Austria, Aragon, Denmark) and subject nations, the additional Diplomat, the Diplomatic Reputation and the Diploslot come in very handy. Also 20% less war score cost is insane: With claims in burgundy, I got picardie, Holland, antwerpen formyself, returned limousin to guyenne (my march) and I had some warscore left, but the AE was already to high ^^ 33% less war exhaustion reduction cost is not a must have, but, to reduce 6 WE for the usual price of 4 WE is still nice. And last but not least the reduced impact of diplomatic actions is very nice. No CB declaration gives only -1 stabhit and +1 WE. This alone saves again MP. Totaly forgot the 25% BROT
So in general (but this is only my opinion) the Diplomatic Idea Group is perfect as 1st Idea Group for England. Btw I decided to roleplay a bit, even though I had 99% WS agains France in the HYW, I wanted to focus on the balance of Power in europe, to kill all potential colonializers and have Marches in Europe to controll the balance for me. For the Bordeaux Trade node I have Guyenne as March. For the Sevilla Tradenode I started to feed Galicia as my March (and I'll use them as Fleet Bases fo further exploration of africa => cape). The Only thing mandatory for me is to own every province in the English Channel. Scotland and Munster (already owning every province except meath) are vassals, and Norway and the Hansa are most likely the next targets. Second Idea Group is already exploration, and #3 will be expansion. Then I'll see how things will develop.
I have to say, that it is NOT ironman, and that I have the mod the 10th Idea.
But I think with England you hava many choices. Basically you can also completely stay out of the european mainland (btw for this event you can keep calais, which I would still strongly suggest for the decision of the stapleport, especially if you dont have Holland, Antwerpen and Caux!!