I use Gas-UK, price went way up during the shortage and is a bit cheaper now but still hasnt returned to their original price. I paid £35 for a 10L cylinder and deposit was about £60. Deposit is fully refunded if returned in 1 year, 80% returned between 12-18 months, etc. Free delivery and collection.
I've been using hobbyweld, there are a few distributors in Aberdeenshire No rental but not the cheapest out there. I think I was £60 refundable deposit plus £30 for the gas
I have a fire extinguisher as well as a co2 bottle. I need it for when the gas runs out as they take forever to deliver. I don't turn my extinguisher upside down as it works fine. Cost me £20