Firstly, welcome to the forum. It looks like you have one of the last Puck L's made. I believe the gas locker on your Puck L should be the same size as on other Tourings.
I recently sold my Triton 430 and I had a Calorlite 6kg https://shop.calor.co.uk/calor-lite-propane-gas-bottle.html next to a Camingaz 907. This Calor bottle has been withdrawn but the standard 6kg Calor https://shop.calor.co.uk/6kg-propane-gas-bottle.html is the same size. Better still would be a 6kg Flogas https://www.flogas.co.uk/product/6kg-propane-gas-cylinder. Flogas are now the go-to provider to the Leisure market as Calor are moving away from it. You could also go for a 5kg Flogas bottle https://www.flogas.co.uk/product/5kg-gas...c=all-cylinders. This was marketed originally as a BP Gaslight but Flogas now seem to have got the design. This photo shows the set-up I used with one on an earlier Eriba.
gas bottle set-up.jpg - Bild entfernt (keine Rechte)
What ever route you take I'd advise a search on Gumtree, FacebookMarketplace, e-bay to see if you can get an empty one cheaply and save taking out an expensive contract. I managed to pick up one of the 5kg bottles for £10. It was supposedly empty but actually has about 2kg of gas in it.

Colin

The regulator should be on the bulkhead of your Eriba. The hoses differ. The standard 6kg Calor does I believe have a threaded end connection to the bottle. The Flogas need a 27mm clip on connector, that also? has a regulator in it.
I find the Hamilton's Gas website is helpful. https://www.gasproducts.co.uk/caravan-ma...s-pigtails.html and https://www.gasproducts.co.uk/gaslow-27m...-top-entry.html

Colin