Llandegla is always rammed on a saturday so business as usual. Get there before mid morning and should be fine.
With young kids we find it much better not to park in the bottom car park (busy and constant car traffic coming / going). Drive up to the top overflow parking – right at the far end. Much quieter and more scope for kids to play. Also parking is quarried into the hillside so take toy dump truck / bruder tractor / spade etc and my boys (7 & 5)are happy for hours when not riding 🙂
The top parking also means very young kids are right on the easy trails with less climbing. Or can do little practice loops dropping down to the cafe on various grade singletracks and then climbing back up on fireroad.
Considering tons of families use it is really strange that the place is lacking even a basic playground.