Has anyone on here topped up their air con themselves? Is there anyway saving to be made ,I’m aware it could leak out ,mine feels coldish but not icy cold.

Halfords sell a bottle you can use yourself, not cheap though. Don't know how they get away with selling R134a refrigerant to retail customers.

Really your current refrigerant needs recovering (if you still have any). Then it needs leak checking, vacuuming to remove moisture etc. before re-charging.

The cans are very hit and miss, I've tried them a few times.  This is one of very few things that are best left to a garage imo.

using a can when you may have a small leak is not worth it esp as the gas you put in could just leak out and add a bit more to global warming. 

You can also buy stop-leak for your aircon system, which I only found out this week !!

I work for a motor factors and we stock the STP Super Seal brand which allegedly works like engine oil stop-leak and re-seals leaking aircon systems. I don't know anyone that's tried it yet, but it gets mixed reviews, so I suppose it all depends on how big a leak you've got ??