I was in London briefly last year and found some good values.
Massage - There is a good place called Nature's Way. A couple blocks down from the Paddington rail station on Praed. Easy to find. Not dingy but not high end either. 50 GBP for an hour. Had an attractive brunette in her mid-twenties. Room was clean and quiet. Relaxing music. After the flip the options were explained: HJ 30, topless 40, CBJ 80. Did topless and at my request she teased and kept me on the edge for a long time. Good experience.
Good incall scene. I used Diva once. No screening you can even use pay phones. Number on the website is "+44 78 80 80 80 70" but from a local phone you dial "078 80 80 80 70". You need change for the phone, starting at 60 pence. The Map function on the website is great - it shows where each lady is located. I saw a hot Romanian brunette with great natural D cups. 150 GBP for an hour incall, about $200 US. 150 GBP is the most common hourly rate, but some charge more. Many ladies also have a 30 minute option for 100 GBP. Very decent pricing and the quality and quantity is excellent. Can't comment on the service in general, but the one I had was good.
Also Viagra is now available in the UK without a prescription.