First, moving abroad is tightly related to visa. This may limit your options very quickly, because unless you have relatives abroad, the main remaining option is to get a work visa, so you have to get sponsored by a company willing to hire you.
With that said, south east Asian could be a good choice indeed. Taiwan and Singapore would be my first choices. Modern countries, safe, with a developing economy, more or less English-speaking people... I may disagree on their political stances (the fight with China for one, the monarchy for the other), but overall, both look to be interesting places, with decent standards of living, and many good opportunities in IT there. The cost of living in Singapore may discourage you though. I don't know how much costs the life in Taiwan.
Hong Kong could be a solution too. As a British citizen, you may find it easier to move there actually. And they still use English as a language to work with, in the administration and international companies.
In Africa, I would mostly consider South Africa and Morocco. South Africa is said to be a beautiful country to visit, has big cities with many IT Companies, and they speak English. Morocco on the other end may be stable enough to live in and has IT companies (often, offshore branches for first world companies).
In South America, I'd recommend Chile. It's safe, vast, with a developing economy. But you'll have to learn Spanish.
Of course, there are always the USA and Canada, and if you stay away from the main cities, you may be able to live comfortably for a decent price. The same with Australia and New Zealand. I assume you considered those countries already.
Finally, Iceland can be interesting, if you consider it to be "out of Europe". They tend to live in autarky since the economic crisis, but there may be opportunities over there.
I hope that helps a little.