I'm pretty certain the vast majority of ISPs don't allow it and it's against their terms and conditions? Most try to throttle you if you excessively upload stuff as it is, if you're hosting a website it'll drain your upload speeds very quickly. Plus it's very expensive hosting in the UK seeing as electricity is so expensive for a server running 24/7, hence why when you buy most hosting online it comes from Texas where electricity is dirt cheap.

You also don't get the reliability if you have a server in your own house, at data centres they have major backups, people there 24/7 to reboot the servers and give maintenance etc if things go wrong. If things go wrong on your server then it can't be fixed till you get home, it's not really doable at all.