White Waltham.
All the comments here are appropriate.
However, as johnm says, the problem is both a licencing and indeed a Health and Safety one. Fire risk and sufficient toilet facilities come to mind.
Hence the club has to be a private members' club to conform. As the club owns the airfield, so there are no other catering facilities on the airfield and, as such, there has no need to be.
The problems mentioned is very real, that of there being insufficient space to accommodate large numbers of people without using the separate facilities utilised for meetings. These are not always available to visitors.
WLAC is one of the largest flying clubs in the UK and so it can be understood that, with a sizeable number of regularly visiting aircraft and their crews/pax, plus members and often their children/guests (obviously all welcome), the lounge becomes exceptionally crowded and the waiting/queuing time for meals/refreshment extends exponentially.
There is thus no facility or even need to increase to include casual visitors.
In the situation of "surely not" though, where individuals have a special interest in the airfield, we definitely do NOT wish to turn them away. Quite the reverse in fact; it can lead to some very informative conversations.
I suggest therefore, "surely not", that you check with flight operations and clear your visit. You and your father will be very welcome.
Oh, and yes, we do badge-check quite often at any time. Bit like your local golf club really ……!