Yeah this isn't really the place for it. But anyway.
First decide if you actually want a lesbian escort (which I'd define as someone who only services women) or if you're ok with one who has male clients but is willing to see women too.
The latter is fairly easy to find. There are lots of women out there working as escorts and a good proportion of them are bisexual at least for work. Some of them prefer women but primarily see men because that's how the market is, some are genuinely bisexual, and some prefer men but don't mind having some pussy on the job. You can't really work out which is which. If you want to give it try you can look through pretty much any escort site, find some girls you fancy in your area, and see which of them take female clients.
If you definitely want a lesbian then you're more limited because that part of the market is too small to really support service providers. You can probably find some women who are giving it a go, though. Try google and gayswap.co.uk.