Hi Anthony,
Information about paying voluntary National Insurance contributions whilst overseas may be found in our leaflet NI38 ‘Social Security Abroad’ which you may find here:
Social Security abroad: NI38
If you wish to pay voluntary contributions after reading the leaflet then please complete and return the CF83 application form which you will find at the same web page as the NI38.
Before applying to pay voluntary contributions you may wish to check your current and future entitlement to a British State Pension.
More details are given here:
Application for a State Pension forecast
Thank you.