'danthevan', you are right they should be hydraulic, however, are you sure about the shimming? I thought that was done to the non-hydraulic tappets.
Here is a 'cut & paste' from my Bently that covers the VW Golf GTI 1985 to 1992:-
The single overhead camshaft is driven by the crankshaft via a toothed, steel-reinforced belt. The cam lobes operate the intake and the exhaust valves directly through hydraulic cam followers which use engine oil, supplied under pressure by the lubrication system, to maintain correct valve clearances. Dual valve springs and both upper and lower spring seats are used on the intake and exhaust valves.
'GolfGiT'
You can change the hydraulic tappets without taking the head off, its dead easy. They are about ?6 each from GSF and all you need to do is take the camshaft off (might be worth doing the cambelt whilst you're in there).
Would you like me to dig out the proper workshop manual procedure for you?