Does this really need servicing/'topping up', or like I've been told by a dealer, that if used correctly and regularly - even occasionally in Winter to prevent condensation build up - should never need attention for the life of the car?
Provided it's working as it should, there's very little 'servicing' neccessary other than checking the belt tension. It may need a gas top up eventually, you'll know when because it won't be as good as it once was.
Provided you use it regularly it'll be fine for some years without any regassing ....and in most modern motors it's actually checked by the diagnostics anyway- when the car goes in for service the system should flag up if there's a problem.
Yes it should be included in one of your service intervals, the check is usually n the pressure in the system. If the system pressure is low it needs reinflating which includes adding fluid
The usual advice is to run it for a few hours at fortnightly intervals if you dont have it constantly running
when cars are manufactured they are only filled with 75% of gas(r134a) to save on production costs, but this gas evaporates at a rate of 15 to 20 percent per year so you shouldnt have to service it for 3/4 years from brand new unless you have a mechanical fault with the compressor/belt or electrics or pipework.
I agree with all above -but DO run they system on COLD for at least 20 minutes every week to ensure that it is oileed - this is the only time it gets oiled according to HOnest John of the DT (Saturdays, Motoring Section) - if you don't get the Dt, it's worth getting on Saturdays just for HJ's helpful comments.