I know the area well, and personally I wouldnt ride there at the moment.
Sure, there will be bits that are OK, but to join these up you will have some really muddy bits that will spoil the overall ride.
If it freezes up your fine, but generally you will need a couple of weeks more of dry weather.
I was up at Woburn on Sunday. There are always dry bits there and we had a couple of hours of pretty much dry riding. The occasionals soft patch, but we avoided the bits that get soggy. Woburn was the muddiest Ive seen it for a while – still rideable, but not completely dry.
Im thinking of Cwn Carn just to get some non muddy riding it this weekend.