Hello, I'm Keith and happy to help you with your question.
When you left the UK in April to work in the Middle East you should have completed a form P85 and sent it to your tax office. HMRC would have made you non resident for the tax year after your date of departure. You will now see how critical that date actually was. Also the tax year in which you depart will be split into two portions, one resident and one non resident. Fortunately there is no time limit on sending in a P85 and it can be done on line into the bargain. On your final return to the UK you merely advise HMRC of your return and the reverse process will take place.
Thus after you come back after April 2015, depending on the exact date, the 15/16 tax year might be split, or maybe the 14/15 if you are on the last knockings of that year. Once classed as resident you will, of course, be liable to UK taxation in the normal manner.
As a non resident you may spend up to an aggregate of 91 days in the UK and still retain your non residence status. These 91 day periods can be averaged out over four years, but the general consensus of opinion from experts on this site is never to exceed the magic 91 days in any one tax year.
Working through an UK service company can cause problems. If you are a director of the company you are an employee per se and must be remunerated through PAYE channels. The company and you could also be caught under IR35 where, even were you not a director, payments to you being subject to PAYE as you are deemed an employee under this tax avoidance rule.
If you are also liable to tax in the country in which you are working there may be a Double Taxation Treaty in force; there are hundreds of these. The aim of most of them as far as individuals are concerned is to ensure than an income stream is not taxed in both jurisdictions. This is done by means of tax credits, the tax paid in one country being allowed against any liability in another.
Well, there you are then, a quick canter through the overseas working life from a taxation viewpoint. I do hope that I have managed to enlighten you somewhat.