Unfortunately CO2 can't be shipped across borders so I'll need to find a supplier within Ireland. I did think of getting an empty tank sent but ran into issues with refilling.
BOC weren't too keen on doing business with me once they found out I wanted to use it to carbonate and dispense a beer keg. They were quite happy to deal with me if I was using it for welding, even though it's the exact same gas bottle
In any case they charge ongoing rental for the bottle which was overpriced for my needs.
That IPT link seems like a good lead - I'll try them out and report back!
[broken link removed] offer this type of equipment, but not sure on how competitive the prices are.
Might be worth chatting to a local pub or two if you have everything except the C02, I'm sure you'd find one who'd let you borrow one of theres (applying a slight markup on cost of course) provided you return the canister.