Here is a list of great resources that will help you prepare for teaching in London, England.
1. Teachers TV - hands-down, the best possible resource to prepare for teaching in the UK. Teachers TV will help you in a million different ways. Watch teachers doing it right, and teachers doing it wrong. Watch, learn, discuss. Brilliant.
2. Guide to Teaching in London: A Survival Guide for Canadians - 110 page ebook that explains everything you could possibly want to know about teaching in London, from a Canadian point of view.
3. ClassTools.Net - as recommended by Mr. Teacher -"www.classtools.net is a new favourite of mine. It has some cool, fun stuff that can be used to liven things up a bit and keep those crazy kids from crazy chaos." You should expect to use an IWB (Interactive Whiteboard) in your class, so knowing what resources to use to prepare fun, interesting & engaging lessons will help you prepare.
4. TES online - The TES is a newspaper for teachers & administrators and most schools post their job vacancies on this website. Don't bother applying from Canada as that's what agencies like Classroom Canada do best for you, but it's still a good idea to look at the jobs & get some ideas. There is also a great community forum on there where you can discuss, share ideas & gain some insight into teaching in the UK.
5. Gumtree -This site was originally an Australian website to help other Aussies in the UK find apartments, travel buddies and jobs. Now it is used by everyone and is like Craigs List over here. It's jampacked with good stuff, useless stuff & spam so be cautious. You'll find heaps of apartments for rent & get some idea of the cost of renting in London. Just don't sign a lease until you've actually seen the place first!
This list will get you started anyway. Please feel free to add more resources in the comments section. Thanks!