I've been lucky a few times and had some spectacular weather, but you are correct that the cool, misty, drizzly days are so quintessentially English. Definitely taking a risk going over in late February/Early March. Did you get out to the Peak District when you were in Manchester? 45 minute train ride from Manchester to Edale, get off the train and it is a 10 minute walk to the start of the Pennine Way . . . and of course you pass by 2 pubs along the way!