G.O.L.D. was a terrible attempt at trying to keep a former famous brand (UK Gold) and shoehorn it into a new format. It was supposed to stand for ‘Go On Laugh Daily’ and the announcers actually called it Gee Oh Ell Dee!
G.O.L.D. was something they were forced into, due to not being able to use the GOLD name at the time, which I believe was due to Gold radio, who they later reached an agreement with.
At the time, they would have either had to keep it as UKTV Gold (which would have been a bit odd if all the other channels had rebranded), or rename it as something completely different, so G.O.L.D. was a compromise.