mate if you are talking about putting darker plastic on...
you can buy a tinting spray and do it yourself you know?
Same rules as applying any spray apply but the effect is decent enough and for ?10 a can would meet all your needs. Personally I would leave the fogs clear, they honestly look better imho. You will lose brightness from indicators and fogs unlesss you use brighter bulbs and attract unwanted attention from insurance assessors should the worst happen!
If you want to smarten the existing look, you can get indicator bulbs with a silver coating, this irradicates the orangey tint you get from the bulbs even with clear lenses. I believe CA Autotech sell them.
If you want to spend over ?100, Mk4 style headlights look much better that the Mk3 items.
If you want to improve safety/visibility/looks, get some decent xenon replacement bulbs which are brighter and whiter than standard or cheap upgrades (I recommend Biolights) and are the next thing down from a full HID kit, which is about ?400 a set!
You can get LED bulbs for the sidelights which are blue/white rather than yellowy too.
Hope this is helpful mate
Ollie