You can call Calor and ask them for help, they do a home delivery service, which is fantastic. You just call them and they bring the gas canister to your house! Fantastic!
I think also, you can probably buy a kit that includes all the gas tubing which you can probably just replace the existing tubes.
I hate to say it, but why not just buy a British one? I have one that I bought from B&Q, its gas, it probably cost like £100, it has 2 burners and its really nice!!! Just last night I was out in the garden in my pajamas (I only BBQ in my pajamas) grilling 2 lovely rib eye steaks. Lovely Jubbley!!!