Greetings Jonathon, and I am sorry for you & your family at this difficult time.
If you father was a member of, or known to a member of a local Model engineering Club, I suggest that this is you best first contact. Even if he was not a member, then contact with them can do no harm. Perhaps your Mother would know of any contact.
At any cost, I would strongly advise against using a dealer or workshop clearance company, they have a poor reputation for value for money.
Perhaps if you let us have a idea of your late Fathers workshop location, we could suggest a suitable club.
Regards
Brian B