Tis easy to do, means removing the dash pod and ferretting about, and on the front of the clock there are two small holes, just big enough to push a paper clip into to change the time.
I think that one in the pick is an MFA clock which is no good to you, you want the basic clock, and its quite easy to fit once you look at the back of the old one its self explanetory. Did mine recently peice of wotsit.
The golf one is the same price from VW as the T25 one so may be the same, looks very similar in diagrams, but wether contacts are the same I don't know - the T25 is a suffix B part -
but are you aware that to fit this you will need to have a rev counter + dash and circuit board, in otherwords you might as well buy the complete set up from a breaker.
If you have one that's not working then usually it is the permenantly live contact on the multiplug for the clock circuit that is at fault, not the clock unit imle.