In the UK I don't think that it's worthwhile to regas yourself as so many places offer bargain regas at around £40 . I have used an ATS Groupon deal several times but it seems they aren't currently offering it. The P38 takes a lot of gas so the cost of aerosol cans to recharge will easily exceed £40.
As far as I can see the only use for DIY recharging is if you system is full of gas but you want to use something like STP Super Seal (sort of like Radweld for A/C) & need to top up the small amount of gas that got vented when you were adding the sealant product.
Amazon product