It appears that Rockys do still make their Goretex Socks, and will sell direct and ship to the UK....
... but while the price is $39 to US customers, it's £39 for the UK and then shipping, duty and VAT brough the basket price for a single pair to a staggering £64 - they're good but they're not that good! (imo)
You might do better by using a US-based proxy-purchasing service such as forwardit.us (or verygoodofyouStephenthanks.com
).
Other possible alternatives have been mentions, from Trekmates or Gore Bike Wear. I found the Trekmates ones a very odd shape after Rockys, short in the forefoot and baggy elsewhere. The Gore Bike ones actually suit me better than Rockies, a little bit wider and less pointed towards the toes. My first pair are lasting well so far.
(As ed said, I've also found the seams on Rockys leak in the end. Even so, I don't write them off when that happens as the leakage is quite slow giving your feet chance to warm the water, which I find enough to extend my usage of unlined shoes into colder weather when a constant exchange of water straight through the shoe to my feet would be unpleasant).