Residence, Ordinary Residence and Domicile
You have no hope of understanding your personal tax position regarding work outside the UK unless you understand these three terms and your status with the UK authorities.
The UK operates three concepts regarding the status of taxpayers. These are "Residence," "Ordinary Residence" and "Domicile." You can change all three of these by your own actions and, though it may seem odd, it is possible to have any of the eight possible combinations of these three!
None of these things is defined in statute, your position with regard to all three is going to be decided by the assessment of a tax man. He will refer to a number of prior court decisions to assess your particular circumstances. Of course, when things enter a grey area such as this, it is impossible to set out hard and fast rules that would allow any individuals position to be jusdged with certainty.
I'm trying to give some general guidence here but, you would need to get a specialist to consider your circumstances in order to be absolutely sure.
Fortunately, there is one area in which the rules are clear and simple. It applies if you are a British based contractor and you leave the UK to take up work overseas. The work must be full time and it must be governed by a contract of employment. It must cover at least a whole tax year and you must satisfy the 91 and 183 day rules. But, if you do meet all of those criteria then you will be deemd to be not Resident and not Ordinarily Resident during the course of your work overseas!
The authoritative, if hard to read version of all this can be found on the UK government's tax site at http://www.inlandrevenue.gov.uk.