Whether you are taxed on income sent to the UK depends on your tax status. Assuming you become non-resident and remain so (in a tax-free country) for four years you will have no liability. Don't forget to complete HMRC form P85 before you leave to request non-resident status for tax purposes.
I would advise you to leave monies to cover costs as you will be charged everytime you send money from the UAE to the UK.
In respect of mortgages, the market here is very different to the UK. Each lender has a list of approved developers so you may not have a free choice. Interest rates are around the 7.5-8% mark and you will usually require at least a 10% deposit. Salary multiples are up to 5 times salary, less other liabilities. Let me know if this is something you wish to pursue, but I'd strongly advise living here for a while before committing yourself.
