>I lived in London until 1994 - maybe it's time to go back? That would be very difficult at present as all of my family have ties in south-west England which they couldn't leave at present.

My partner live in Sevenoaks, Kent(you know that some people hate to live in London).
But almost every day he travel to clients and present work done till this moment. Most of them do not require he to be everyday at their office.
There are ways to serve 2-3 clients and to make the same money as till this moment. I understand that most of the people prefer to explain to programmer what they looking for, becase they could do the same writing the e-mails or calling by phone.
If appears larger project there are always UT members which will help you fast to do it in required term.