Just got an email back from the DVLA
Thank you for your email.
Driving licences are valid until the drivers 70th birthday unless a short period licence is issued for medical reasons.
The photograph on the photocard section of the licence must be renewed every 10 years.
To apply for a GB provisional driving licence you will need to complete application form D1(available from most main Post Offices®).
The forms will need to be completed and returned with one passport sized photograph, a cheque or postal order for £50.00 and a valid passport.
Once you have been issued with a provisional driving licence (and the commencement date is in force) you are able to commence driving lessons/ contact the Driving Standards Agency (DSA) with a view of booking the appropriate driving tests.