In my experience the compressor is pretty sturdy and they don't often fail also not being used for a long period didn't affect my rover 827vitesse. I bought the car off my brother inlaw with aircon not working, I had it gassed by mobile guy and it all leaked out. I could see pipe that was leaking. I didn't bother for around 3 years to sort it and don't know how long it wasn't working before I got the car.
When I decided to change pipe a couple of years later I had my brother inlaw to vac it down and re gas system. It did work first time, there was a bit of smoke initially from compressor as clutch plates cleaned themselves up but after a minute system was A one running smoothly and ice cold. I had no issues after that for 8 years just topping up system myself with a Halfords re gas kit.
My ZS also had non function aircon when my son purchased car, he wrote car off that winter ( not much damage , just stupid insurance ) and I got car and repaired changing one front aircon pipe. When car was back on the road I did a climate control conversion from aV6 ZS and decided to have it regassed. Again I don't know how long it had been faulty but after my brother inlaw vac testing and regaling it worked perfectly and still does.
So hopefully yours will do the same, would not worry to much about it. Get the system vac tested before any gas put it, this will tell you if system is holding pressure or has a leak. All being good system can be gassed up and you will be sorted, another thing to say is this time of the year can be a good time to have it done as air con places are usually quite so it can be cheaper ( not as cheap as having brother inlaw do it lol ) but shop around it's worth looking.