Yes, been there for dinner once (knew one of ex-committee members). Not particularly stuffy, and you can just turn up and use the place if you are in affliated clubs etc. People in fairly ordinary smartish clothes, nothing out of the ordinary for most clubs. Food OK in a clubish sort of way. These days anyone can join - you don't need an RAF connection any longer. Take their traditions very seriously, I hear they are quite hot on members flying ensigns etc by the rules.
Arthur Wood stayed there for last year's forum get together. I booked him in and was convinced he would have to know officer ratings and would be asked which squadron he had flown with. Turned out to be quite informal with no difficult questions. Restaurant looked good and it was a pity we had to go to the forum shindig! Room was comfortable and tidy although not ensuite.
Lovely spot and could be worth a try depending on what you are looking for.