I don't think 27 is too old. It will probably take you about 5 years to get a licence and be well paid, but then you can go to any company anywhere.
I used to work in a light maintenance company and it was the guys who were studying for their part 66 who got taken on and sponsored, rather than those who had no experience.
Right now I think there is more opportunity in helicopter maintenance, and there are quite a few companies around the London area.
Good luck
