There are a few people in these forums that buy and sell gold for bitcoins. Look here:
https://bitcointalk.org/index.php?board=51.0But if you work in the bullion industry, you are probably going to be able to get a better price for the gold through your own connections. Buying bitcoins is probably not difficult in the U.K., though I don't know the best way. My guess is that you should go through Bitstamp or LocalBitcoins.