Hi
There are many clinics in London...
You may need to look some up in a directory, and go and visit a few. If you like the look/feel of any of them, you could ask about availability and take it from there.
Some clinics will be looking for practitioners, others won't be interested... Some won't want to take newly qualified practitioners etc.
Building up a practice just takes time. Talk to as many people as possible; talk about how acupuncture helps people; treat as much as you can, even for very very little money! In time your patients will become walking talking advertising for you, but you have to get them better first!
Personally, I get minimal patients from leaflets, a few from the Yellow Pages, more from my website, more still from passing my clinic, and the most as recommendation from existing/past patients.
Hope that helps some!
Aragorn