https://www.halfords.com/motoring/engi ... 64627.html
So ordered a bottle of climate change with the pressure gauge for £60 in February when we last had good weather as my cars were feeling pretty weak. However it’s only this weekend that the weather is warm again. Topped my 3 cars which were all on the low side and they’re way better now.
Proceeded to try and top up the M6 as it has a weird problem which no one could diagnose - it holds AC pressure for months - like up to 6 months then randomly one night it let’s it all go. However I think it finally hit the point of properly fvcked as it was immediately losing pressure today.

Anyway I can still feel a bit of liquid sloshing around in the bottle so I’ll use the rest to top up the X5 when it’s back from the body shop.
It’s well worth it if you need to just top up a few cars.