I think this thread is already fraught with urban myths, misleading, misguided, uncited and downright fiscally dangerous information.
The relevant rules and regulations are contained within HMRC6. http://www.hmrc.gov.uk/cnr/hmrc6.pdf
This replaced IR20 (previous legislation) within the last couple of years.
A quick read of the document will leave you in no doubt that the application of taxation is now completely subjective.
Taking "professional advice" (as HMRC advise) is also a waste of money. Tax "professionals" do not provide binding rulings. HMRC do that. And if HMRC want to see things differently from your tax advisor, there's only going to be one loser. And it's not the advisor.
Here's my 2-penneth;
(1) IF (you want to leave the UK to save on tax, whether income, inheritance, capital gain, national insurance etc) AND (you suspect that you might go back at some point in the future) THEN (forget it). When you do return, you'll be bent over a barrel.
(2) If you want to leave the UK for a "higher quality of life" or "standard of living", then you probably have the right motivation - and a choice of 100+ countries in which to realise this dream. However, wherever you go, you will need to integrate with, and embrace, the local language and culture. This does not mean that you'll, in return, be reciprocally accepted and welcome by the indigenous peoples - but it is a start.