Hi. My name is*****'m looking at your question now and will post my answer or ask for more information here in a short while.
Can you give me your projected earnings and tax deduction to the end of October 2016 please. Do you have any employment benefits such as company car or private medical insurance? What tax code are you on at present?
Even though you only worked in the UK from November 2015 to April 2016, you are still entitled to a full personal allowance for 2015/16 of £10,600. If you didn't call HMRC to have your tax code checked, you may have been on a Month 1 code which means that each month is dealt with in isolation and there is no accumulation of personal allowance as the year progresses. By the end of September 2016, you should get a P800 tax calculation which will show whether you are underpaid or overpaid. You could try to accelerate this by calling the tax office on the number here and asking them to review your 2015/16 tax postion and to tell you where you stand. You are probably due 7 months of unused personal allowance of £6,183 (£10,600 /12 x 7) but unless I have the actual P60 fgures for gross pay and tax deducted, I'm reluctant to give you a figure as I don't know how you were taxed in the period to 5 April 2016.
Based on the 2016/17 earnings and tax figures, you will be due a repayment of £4,496 if you leave your job at the end of month 7 and leave the UK. If you do leave the UK, complaete a P85 to get the overpaid tax back.
I hope this helps but let me know if you have any further questions.