There is an ongoing conflation of domicile and residence. If you were born in the UK it is almost certain that you will remain domiciled in the UK for the rest of your life. It is notoriously difficult to lose that position. What you are almost certainly talking about is residency for tax purposes.
And I still don't get the OP's position:
Where is "here"? My assumption is Thailand. And what do you mean by live? More than 180 days so you are clearly a resident in tax matters. You mentioned earlier that you spend most of your year in KSA, which means that you live there, not "here".
In any event, you can easily open a pound sterling offshore bank account in the Isle of Man etc.
If you attempt to open a British onshore bank account then they will not allow it unless you lie about your place of residency. That is, as I explained earlier, a crime. The bank will ask you for your tax ID. What are you going to do?
The money might not be taxed in the UK or Saudi Arabia, as you've pointed out, but that does not mean that Thailand cannot tax it if it enters Thailand such as via an ATM withdrawal, should you at any point be resident of Thailand.