The main site here answers some of your questions about getting started. There are links for places to advertise, photographers, web designers, and places to build a free website.

Unless money's really tight I don't recommend getting a free website. They have limitations (Moonfruit, the most popular, doesn't show up in search engine results; ads on your site and a url that makes it obvious you're using a free site make you look less professional and if you pay a bit for your own url you may have trouble moving it when you get a real site), which I don't think are worth it when you look at how cheaply you can have a good-looking template site set up for you by a webmaster. Also, the time you spend making a free site will be worth considerably more (in escort rates) than what you can buy a website for.

For fees, you look at the range of prices in your area and then decide whether you want to charge low, medium or high rates in relation to everyone else. This is more complicated in London though because there's such a wide range.

Why London though? Do you want to avoid working where you live? If not, advertise closer to home and say you also cover London. You don't need to be another of the thousands of escorts operating in the capital.