The only information that you need to see if he served in the RAF (and he did by the picture) and to receive his service record
is
1. Month and Year of Birth
2. Full name
3. Proof by means of a digital copy of death certificate (jpg photo acceptable) of his death at least 25 years ago.
Follow the online application procedure for RAF Records of Deceased Service persons in the links you have been given at GOV.UK.
If a record is found matching the information you gave in 1, 2 and 3 then they will request a payment and after a defined time subject to demand it will be emailed to you.
Ross