I'm from the UK, but now live in the States.
I'm not a really heavy keyboard user, so there may be problems that I haven't come across, but for the most part the difference is small enough not to matter.
I'm typing this on my laptop, which I brought with me from England and thus has a UK keyboard.
I'm using Ubuntu, and I selected the US layout, because, well I have to get used to it sooner or later!
The main thing I needed to relearn was that @ is now above 2, and " is now above '.
This made searching for exact phrases on google, and typing email addresses really annoying for a few days, but I got used to it quickly.
My friend used to have a Mac, and her keyboard had these symbols switched too, but I think it was a UK- purchased laptop.
I still haven't found my pound sign, but I haven't really needed it (I just type 'quid' when talking to my UK friends...) This may be a problem for you I guess.
I'm afraid I know next to nothing about the finer details of layouts, but is there anything stopping you from telling your computer that you have a UK keyboard and just ignoring the differences in the symbols on the keys, or would that cause problems elsewhere?