Hi,
There is only a requirement to register for VAT in the UK if you make taxable supplie sin the UK over the threshold of £90k.
However you can register for VAT voluntarily if you make supplies which are Outside The Scope of UK VAT but which would be taxable if made in the UK.
Please see the guidance below, specifically section 2.9:
Who should register for VAT (VAT Notice 700/1)
If you do not meet the critera to register for VAT on this basis then you will not be able to register for VAT.
If you are able to register for VAT voluntarily then you can deregister from VAT at any time.
Thank you.