Tax form

This is a complex matter, and the outcome could mean you pay tax only on your UK income (if any) and/or on income you transfer to the UK, or on all your income. You may or may not be charged a substantial fee to pay tax on the remittance basis. 

First I would suggest you read the HMRC guidance, particularly in relation to domicile, resident, and ordinarily resident.

Also you may become "resident but not ordinarily resident" but your spouse (if any) may have a different status and may be taxed differently. This is equally an important matter.

Like I said, reading, then re-reading the HMRC website and guidance is the first step.  This may take you 4 or more hours. 

hmrc.gov.uk/international/leave-uk.htm

If you don't have the time or still don't know what to do I would suggest that you try a tax advice website, or a specialist tax advisor.