As well as the coastal path you have the Coppermine Trail. This is more towards the north of the island/amwlch/cemaes bay and is (apparently) rideable ( never done it, so don’t hold me to that!). Loads of good wild camping around church bay/cemlyn bay. The fish n chip shop in Cemaes is excellent.
The all day breakfast at the Wylfa Power Station visitor center cafe is worth a detour. (took the little ‘un in last year when it was hoofing down)
If you need bike spares I think Valley has a very small bike/Canoe shop.
Hope the weather is good and enjoy. :-)