I did this on my A4 you only need the discs and carriers if ATE (not the callipers) so the pads are the same size it did improve the brake effort but in the wet before fitting bigger shields the brakes needed more effort.
Just remember also that you can not go up to 312mm and use 15 inch wheels min 16 inch depending which carriers you use you may need to space them away from the hub.
I did reuse the Audi/vw original pads on both 288 and 312 and the difference in the dry was worth it now I am using EBC red stuff which again improved it even more. I wouldn't bother with drilled or grooved discs just a set of standard 312 mintex, ate or pagid unless your using your Golf for track days.
I am not sure about the lucas/girling set up only the above info is for ATE front brakes.