Classic British Flight Sim

Having finalised our holiday back in blighty, we have booked a cottage in north wales for a week based near Porthmadog. so i ask if anyone has ideas as to what to go and see around. the train trip on the ffestinog up to the quarries, also the underground trip are on our list.
so which is the best castle to visit? ( have a five year old in tow )
whats the best beach to go on? ( have to spend some time soaking up the sea air before returning to my landlocked home.
what else might be of interest. trying to cover as much in one week. only north wales. the rest of our time is based in leigh lancs, have days trip to derbyshire/yorkshire and the martime museum in wallesy.

Check carefully the Wallasey maritime museum - if you mean the WWII submarine etc I fear it has closed for the moment at least. The Maritime museum in Liverpool is well worth a visit - a ride on the Mersey ferries is bracing if you are normally landlocked - and at Leigh you are only about 1.5 hours' drive from the RAF Cosford museum which has many unique exhibits ( though not, sadly, a VC10 any more)