I have stayed at Trawsfynydd Holiday Village a few times now with my riding buddies, its about 2 miles from CyB, they are Log cabins ( don't be thinking of Switzerland, more really big garden shed ) its cheap enough if there is a few of you and have cooker/ fridge/ shower TV/ Video/DVD etc plus there is a PUB onsite which does pretty good food although you'll probably have to book if you're going in the summer as it can get busy. They are mountain biker friendly, although there ain't anywhere that you can store your bike, BUT its pretty much mountain bikers whgo go there anyway so people pretty much lock their bikes to there cars/each other. Or if you ask when you book up, some cabins (6 berth) come with a sort of conservatory part on the front with loads of room for bikes, although I would not tell them thats what you want to use it for!

Hope this helps?