Air conditioning recharge

After buying my GDI last October the air conditioning appeared to work but not very cold.
This morning took it to Kwik Fit (UK service centre chain) and they hooked it up to their machine.
Looked promising with pressure in the system, so it was vacuumed, leak checked, and refilled.
There was about 30% weight of refrigerant remaining in the system, and looking at the car history it probably has never been recharged from new.
Hopefully if used regularly (I never turn a/c off even in winter) it should be good for while. Not bad for a 19 year old car.
Just need a decent summer now!