Welcome to Wild About Britain, Vixen.
I'm sure there will be members of the forums who will be able to suggest where you might go to offer your help regarding wildlife rehabilitation. I'd be pretty surprised if there were no hedgehog or bird sanctuaries, for example, near you. There are one or two listed in the Directory pages of Wild About Britain -
http://www.wildaboutbritain.co.uk/directory/ - so you could try them initially. Yellow pages list Animal Welfare Centres and Conservation Organisations too. If we can find any more we'll let you know.
Good luck - it's nice to hear from someone who wants to 'get their hands dirty'!