WRC's English Campaign Strategy:
I think the best thing for an English player to do is to play the diplomacy/trade/naval game. Much like Britain in history, try to play rivals off one another and pick your spots to go to war.
The English have a really strong position (and units) for defense, and a really weak position (and units) for offense. The English should focus on their strengths - defense and trade. Spam diplomats out to every Euro nation and secure trade agreements. I would suggest the HRE and Italy as natural allies against your natural foes Spain & France.
England really shouldn't start off trying to blitzkrieg the continent - it *should* find itself hopeless outmatched by the French & Germans in such a war on their turf. Instead, first focus on the Scots & the Irish. Once you have Britain united, that should provide enough $$$ to field a small navy. This navy will be the most important part of your military because it will allow you to move stacks around a large, disassociated empire quickly.
Using this technique properly, you can use 1 Stack to control large swaths of coastal territory by constantly moving to where the action is. You can also use hit & run tactics to confuse the AI (think vikings) -> If you were fighting in Spain, let your stack offload on the northern coast & siege an AI city. When the AI responds by sending reinforcements, jump back on your ships and sail to the SW coast of Spain faster than the reinforcements could possibly walk. Now you should be facing a very lightly-defended settlement. If you want to really abuse this, sack the settlement, sell/raze the buildings, and sell the settlement to your ally for $$$. If possible you can also ask the ally to declare war against the enemy in exchange for the territory / $$$. That way the enemy AI still comes after the city it just lost. Then load up your armies into the ships & repeat on the other side.
Britain should strive to continue building a naval empire without engaging major powers in war. One can try to take the Flemish territories, but that may result in France having a go at England on their turf. It might be worth taking a Flemish settlement & selling it to the HRE or the Italians for extra cash. If you are allied with HRE, I would suggest attacking Denmark, who isn't so big that you can't take them on early. Taking over Denmark allows you control over the Balkan Sea & allows you to begin to encircle the continent (& maintain a check on your HRE ally). This will also provide insurance if Kiev or Novogrod ever become too powerful as you control access to their ports.
From there, I'd assess the strength of both Spanish factions & Portugal (using the faction rankings graphs) and decide if you can afford to take either or both of them on. I'd recommend sticking to the Atlantic coast of Spain/Portugal at first, which keeps everything within 1-2 turn naval range of England. This way your supply chain won't be much longer than the Spanish who take 1-3 turns to walk across Spain to the Atlantic coast.
From here, you should be ~30 turns in, and gaining steam. The English units improve through the ages, so its almost a waiting game until you get Longbows / Knights that can stand up to any army mix. Just keep nibbling up rebel territory on the coasts, avoid invading France & Germany, and abuse Crusades for free XP & upkeep. If you took Atlantic Spain/Portugal, you can start inching into the central Iberian although make sure you don't overextend - the English advantage lies in maximizing coastal maneuverability!
For my mid-game I like to take Gibraltar & the western North-African coast, then launch into Sicily. If you control Britain, Atlantic Spain, Denmark, North Africa west of Tripoli, and Sicily, congratulations you now have Western Europe surrounded. You should have enough cashflow to take on the French, and strategic superiority due to the fact that you can attack them from all sides at will. Launch naval attacks on them from the Mediterranean South & when their armies move to counter you take out their northern coast with your big army from England. If you add France to the list of above territories you shouldn't need any more guidance from me - its time to let everyone else know its time to bow down or die.