Down here , the Exedy brand is most highly rated; but many others are good too.
But... from the information you have supplied so far, I think you only have one oar in the water.
"....the oil (sic) change gave me a good few months of symptom-free driving ..."
If your clutch is weak or worn, it stays that way. No Easter resurrection, irrespective of any devotional expectation.
"...a lot of air came out ..."
a defective clutch ( pressure and driven plate) cannot force air into the hydraulic system. 'Hydraulic' is where you problem lies.
If you have a new master,
no fluid leaks, and have correctly bled the system ( reverse bleed?), there should be a firm pedal.