We are unable to advise regarding digital nomad visas, as this is not a tax matter.
You can ask your UK employer to write to HMRC and seek a direction to operate PAYE on an employees earnings or complete the online form here:
Apply for a direction to operate PAYE on an employee's earnings
You can find guidance on National Insurance here:
National Insurance if you work abroad
If you need further information on National Insurance you will need to contact our National Insurance team.
National Insurance: general enquiries