If weather stays like it is now you would be far better getting out on the natural stuff. Save the trail centres for winter or bad weather days. Appreciate it is hard coming to a new area to find stuff worth riding. But I reckon if you say exactly when and where you will be and what you want to ride there will be people on here going out willing to show you round. Either that, or grab a map and hit the tops. Almost all the ridges between the south Wales valleys have some XC riding on them, some better than others, the trick is knowing how to link it all together to avoid towns and traffic.
If you can get up towards Abergavenny one evening next week (probably Wednesday) then I will happily show you round the Black Mountains/Aber area