Note also that Good Friday and Easter Monday are public holidays in the UK. The shops and museums, etc, will be open, though. If you do want to travel, note that it'll start getting expensive very soon (if not already), and that everything travel-related will be horrendously busy. Heathrow on the evening before any public holiday is bad (bad enough that I've taken to working on public holidays and taking a day off the next weekend if I want to go away), but Easter is worse than most, because of the long weekend.

The restriction on shops opening on Easter Sunday only applies to those over 3000 sq ft. That said, it's usually very quiet. I'm pretty sure most museums are open: Bank Holidays usually see an mass exodus of Londoners, with a mass inpouring of tourists and day-trippers. There's also usually a handful of events around the country - nothing remotely on the scale of say, Semana Santa celebrations, but worth looking out for.