Lorraine,
We've done the trip from Widnes, Cheshire to Fishguard with the van a couple of times via the M56, M53, A55, A483, then gone cross-country through Welshpool etc down to Aberystwyth, then down the coast road. It's very scenic, and the roads are brilliant, but can take between 4 and 5 hours including a stop. I thought of using the motorway the last time, but the lure of the country roads got me.
Good luck whatever route you decide upon.