Coolant had to be topped up on VW Golf by 1L in approx 3 months - Normal ?

There could be a minor leak on your radiator. Our citroen people carrier was very low on coolant (none in the bottle) when it went for its last service. No coolant was visible on the tray or under the car but the garage found a pinhole in the radiator.

Open bonnet on a calm day when engine is warm , inhale through your nose , do you get a sweet taste in your mouth suggesting there is a leak. Plastic housings on the side of cyl head are known to weep and getting a big build up of Dry antifreeze. Thermostat housings are a weakness because they are plastic and the seal no longer sits in the non existent groove.

Water pumps are another source of leaking and to see that car needs to be on a ramp with lower shield removed.

Have a look around all hoses for fuzzy growths suggesting a leak

Water pump usually means timing belt kit , if there no sump shield on car one would see leakage traces below crankshaft pulley.

Make sure thermostat housing is looked at also.

You never mentioned what engine it is in the car.

Like this one?

https://www.google.com/search?client=opera&q=vw+1.2+water+pump+location&sourceid=opera&ie=UTF-8&oe=UTF-8#fpstate=ive&vld=cid:68d0bbfb,vid:Ct9og6QiufY,st:0

Another video

Do you not have a mechanic you get your car serviced by?