Hi Mike,
You should contact the Pension Service for advice on your personal circumstances.
HMRC are unable to provide advice on whether you should pay voluntary National Insurance contributions or not.
Once you have spoken to the Pension Service, if you wish to pay voluntary National Insurance contributions from abroad, please complete the CF83 application form which can be found here -
Social Security abroad: NI38 - GOV.UK (www.gov.uk)
Please read the information on the NI38 before completing your application form.
The contact number for the Pension Service is +44 (0) 191 2187777, lines are open from 8am to 6pm Monday to Friday.
Thank you.