David, you have every reason to be proud of your father and I hope you will be able to provide some suitable tribute in time for July.
In the meantime, I do urge you to try and obtain some permanent record of his activities. It will be painful, but what is more painful is the fact that his memories of others, who paid the ultimate price, will die with him.
In a way, he owes a small debt to them, to ensure that their sacrifice does not go without due recognition.
See if he will do it for them, not himself or you. It may help ease his mind, too, and no doubt there will be many happy memories in there too...
Look for the silver lining!
You could start by introducing him to the classic thread here "Gaining a Pilots brevet in WW2" and see how closely (or not) it relates to his experiences, as well as a memory nudger!