Hi Karl,
I have my doubts about the local Council round here sometimes and their ability to provide even the most basic of services for divers - be that off RIB or hard boat.
Anyway, AFAIK there's no charge for Amlwch Port slip and free parking (if there is a charge the H/master is never around- another skiving council appointee) Can be a bit awkward- need a 4x4 and break-back type trailer but harbour is very solid all the way down to the sill.
As for hardboats- your welcome providing you're willing to risk being lured to the yellow-side
ATB,
Terry