Totally appreciate where you are coming from. I have been in that place many times before. There is some excellent ips already been posted here. It is usually a case of gritting your teeth and just getting on with it.
I'm a fellow Brit and I've been running my web biz whilst travelling for about 5 years and totally reccomend that you do it. The visa's taxes, and banking thing can be tricky and is always changing but once you've made the jump it only gets easier. I have been running my online businesses whilst travelling around South East Asia and it totally rocks. mostly renting places in Thailand as a base (and once you have an address you can get a local bank account and other stuff) then because of the different visa rules you have to leave the country every 2-3 months anyway which I like as it sort of forces me to travel more and discover the other places around South East Asia that also support theis lifestyle, Bali, The Phlippines, Malaysia, Singapore, even places that are lesser developed like Laos still have solid internet connections and it is possiable anywhere. The obvious massive bonus is how far our britsh pound goes whilst living in these places. Still having an address (a famliy member or friend)in the uk is real handy also. So you are sort of registered as living in the Uk but travel alot. Then you can keep you existing english banks going.
The biggest tip I can offer is buy the plane ticket and everything else will fall into place.