my family lives in the southeast, the bournemouth area, which is actually now more expensive than London, but salaries are lower
I'd consider Bournemouth the South West, not the South East. There's a lot of retirement types that have traditionally moved to Bournemouth (think Florida). So I guess it depends on what lifestyle you want to live.
Granted, London is a big place made up of lots of widely varying areas each with their own costs of living. If you're talking Central London (average house probably about £600,000) then I'd find it very hard to believe that Bournemouth (average house probably no more than £250,000) is more expensive.
Anyway, I know IT jobs were in a bit of a dire state a few years back, I could barely find much in the South East and nothing anywhere else in England. Nowadays, perhaps the market is a bit better? You'd do well up North with a good programming job, even though you could earn a fair bit less the cost of living would probably outweigh that.
Good luck in whatever you end up doing.
Matt