I would use Fishguard ( Goodwick ) personally . Wide concrete slip accessible hightides +/- 3hours ( possibly a little more , but take local advice on that ! )
Several designated parking bays for cars plus trailers , cost £ 1.50 per day in 2015 . Launching itself is free .
You probably can get closer but immediate local launching will be both size and tide restricted . Goodwick is a pleasant spin away round Strumble Head .
Watch out for families on the slip and the rocky Pembs. coast .
Should be a lovely day out if weather is good !
I see DHF has just beaten me to it........
Checkout DHF's Flikr site.....