Try your local Service Flying Club - they can normally help out veterans even if it’s just a temporary membership to get your licence sorted. Prices likely to be 2/3rds of commercial rates due to non-profit status. If you have an enhanced learning credit left then you can use that as well.
https://www.raf.mod.uk/rafflyingclubs/
Yeovilton Flying Club | Home of the Yeovilton Flying Club
Army Flying Association
