What sort of standard is Royal Ascot CC mate? I'm working at LVS Ascot from September and was looking for a club round there. Considering Burnham, Slough or Windsor.
Of the clubs you mentioned, Ascot are the weakest but their 1s still play a good standard.
If you want a social side to your cricket then I would scrap Burnham and Slough.
Windsor are currently TVL div 1, and from what I've heard from a new player they've got they are seeking to seriously challenge for promotion to the Home Counties league this season.
There are plenty of clubs around the Ascot area so it all depends on what standard you are, what standard you want to play and the social side of things.