Cam Shaft Tapping

I have quite a loud tapping noise coming from inside the rocker cover and a friend told me it means the camshaft needs replacing. Before I go down that (expensive) road is there any adjustment that can be made. With my limited knowledge I recall that on some engines you can adjust the tappets? Mine is a 1986 1800 GTI.

Any help appreciated.

When do you notice it, when it's cold, hot or both? 
What's the mileage on the car? 

I've only really noticed it when it's cold. Once you're driving you don't tend to hear it. The car is 1986 and has about 89,000 miles.

Well they are a little tappety when cold until the oil gets all the way up there.

Mine lasts anything up to two minutes from a cold start, depending on how cold it is over here. It's a 1990 with 57,000 miles.

From cold, let the engine come up naturally to normal operating temperature and stand there so you can listen. 
You might just find the noise fades as the temperature comes up.

Your friend may well be right but I'd rather do that first then start ripping the engine apart!   

Don't listen to your friend there's nothing wrong with the cam shaft, it's just the hydraulic tappets.
How old is your oil and what grade of oil are you using?

also if you use a cheap oil filter these often lack the little valve inside that stops the oil draining out the head after you switch the engine off, which results in more tappety noise till they pump up again. also could be tappets are a bit dirty and a good oil flush can sort this.

first up check the filter, if it doesnt say MANN and/or have any vw marking on give it a service with fresh oil and proper filter:
AVS Car Parts - [The VW - Audi - Seat - Skoda Parts Specialist]

I use quantum synta silver or fuchs titan xtr 10w40 on all my dubs and this does the trick nicely, but most semi-synth 10w40 will do you just as well tbh

Thanks everybody. I'll change the oil and filter and take it from there.

Does 86 model have solid or hydraulic tappets ,if needed u can tweak shims .