thinking about getting a pair of sealskinz for my impending trip down the wye, anyone know if a) they are worthwhile and b) a decent online supplier or a store in the liverpool area which sells them?
I would not say they are worthwhile. I have the thermal socks and use them for mountain biking and they have soon worn through and are certainly not waterproof. They have a strange feeling to them like your putting your foot into a bag, and they take forever to dry, add the price to the factor and you have yourself one very expensive and naff pair of socks.
They do take forever to dry, but they are waterproof (at first anyway), just not very breathable. I wear them in fell shoes and on the bike and I like them a lot. I have both weights of the merino lined ones, for hill routes or long days not running a light liner sock improves comfort quite a bit for me.
Another option is TrekMates GoreTex oversocks. Like the Sealskinz they feel a bit weird at firts but are actually pretty good.
I've found that if it's a bit wet they will keep your feet dry, but in serious wet they get wet (possibly condensation inside?) and then they are awful: take ages to dry, feel cold and nasty. For a day walk, maybe Ok, for backpacking I'd say just get used to wet feet (and have dry socks to wear in camp).
I have 3 different weights, the originals, the mid thermal merino lined ones and the new thiner short cycling ones and would recommend them. They're certainly waterproof IMHO, however once wet they do take ages to dry. Also don't put 'em in the tumble drier, as they separate.
I bought a pair of their gloves for my wife who is a sea kayaker and they were not as described, being seive like and slippery on the paddle. They were returned to the shop (on the mainland) the next day and a refund was promptly given, though the sales blurb extolling their virtues was by a kayaker!
