In reply to John Rushby: John I agree with Pat, you have to try them out first. I tried a Mega (their place is just along the coast from where I paddle) and it was OK, but I couldnt get on with the hatches, very fussy things. I paddle an NDK Explorer which is supposed to be tipsy (as in not very stable!) but I think its great. I bought mine second hand from NDK, I saw them at sea kayak symposia on North Uist and Wales, gave me a chance to try it out and I was hooked!
Plastic would be OK for stony/rocky beaches and they are cheaper than 'glass boats but a bit slower. Fibreglass is sweet, but quite fragile so no seal launches! There are several websites with kayak reviews and Sea Kayak mag is good too (but its Yank and only out every two months). There are several British mags but they deal with all paddling. A European Sea Kayaking magazine is desperately needed!