Great Britain pretty much rocked. There are a lot of castles, history, wonderful walking to be done. Josh and i stayed in a castle youth hostile in Wales, and had not enough time in London, and didn't even get to head north at all. Never mind Ireland. You could spend a week in London going to see museums and stuff without getting bored. But then, i'd live in London in a second.

At any rate - don't go for a weekend, its totally not worth it. i think crossing the atlantic requires at least a week of time, preferably more.

FWIW, my understanding of London weather is that its similar to Seattle - so, um, not nice in the winter, but not undoable. I do not know how 'bad' things would get as you went north. Frankly, though, i've never found the weather to be a hindrance while traveling, just the non-peak hours kept by some of the things we wished to see.