Everyone needs a doctor. Best thing about London, its free! Thank you NHS!
This is REALLY important. If you come from a country where doctors are everywhere and you can walk into a clinic for treatment or a casual chat, please know that you cannot do this in the UK. I've heard many stories of expat friends falling sick and unable to fix an appointment with a doctor. By the time they do, most of them would have recovered. While there are private clinics around, why waste money a pay for service which is paid for by the exorbitant London tax rate?
NOTE: It takes an average of 1-2 weeks to get a doctor's appointment in London
The moment you settle and have decided where to live, the first thing that you should do is to familiarise yourself with the nearest GP in the area. Walk in and register yourself as soon as possible. This is a simple step that will sort you out for the rest of your time in London. Once registered, you will be under the wings of your local GP who's essentially your doctor for the rest of your time living in the area. You will also be given a NHS number which will be useful for any medical treatment that you seek going forward.
Please do not wait till you fall sick before registering yourself. However, if you are in severe pain and have never registered before, you can still call 999 and let the emergency services sort you out. They seem to be always howling on the road any way!
Again - just walk in and sign up with a GP as soon as you can. It doesn't take much time.