If Sunningdale is not available then:
Staying in NW london try Sandy Lodge - often overlooked but a small charmer.
Stoke Poges will be easy to get to.
If you're close to the M40 Huntercombe is within easy reach.
If Swinley won't let you on, the Berkshire won't dissapoint.
"Wentworth is the golfing gods way of telling you, you have too much money"
Or be perverse and opt for a rather good, and very affordable RTJ at Stockley Park.
Enjoy.