There IS gold to be found, judging by the gold mines in Cornwall and Wales, and the traces found in Derbyshire fluorite mines. Also, at one point the World Gold Panning Championships were held somewhere in Scotland. Check geological maps and surveys for likely spots, but be warned that you're not likely to find huge nuggets of native gold: small flecks and gold dust are more likely.

Occasional hordes containing gold turn up from time to time as well, usually found by people with metal detectors and a stroke of luck. Often dating from the Dark Ages and tending to be collections of coins, rings, brooches, and other pieces of jewellery, these finds must be reported to the relevant authorities if they're of any size beyond a couple of coins. They tend to end up in museums, but whoever found them does get paid for their find. There was a find a couple of years ago of a Saxon sword with gold wire work on the remains of the hilt, and a more recent discovery of a sealed cup full of coins.