http://www.londonfetishscene.com/
I think this is a great site for planning a London trip. Both Regulation and Expectations are listed by them. Both stores are very large and stocking plenty of things I couldn't even begin to guess how to use.
edit: I almost forgot. Fettered Pleasures, (also listed on the site) is another great one, and the only one I've mentioned that have specialised toys to be used on women. Most toys can be used on both sexes, but gay stores will never stock fluffy cuffs and pink dildoes.