Hi & welcome to the forum. I have a designer as well, good choice.
Choice of gas depends really on what you want to do.
Calor butane cylinders, 4.5kg no good in low temperatures towards freezing.
Calor propane cylinders, 3.9kg good in all temperatures.
Camping gas, 2.8kg cylinders are actually butane, so no good in low temperatures towards freezing either but are small and light.
So really depends on whether you want to do winter camping or not, which is perfectly doable in a dandy. If you want to winter camp, propane is the only choice, if not butane or camping gas are fine or you could use propane.
If you don't want to use electric for heating and kettle etc you will use more gas so may want to use a larger cylinder to save money.
Whichever you use, you need a compatable regulator although now I think they have a universal regulator but with a tail connecting pipe with a different cylinder connection. All 3 types have a different connection.