So maybe you're wise to take a stove to cook on the fly. As for what kind, no question about it: I'd take a canister stove. White gas is not used nearly so much in Europe as it is in the U.S., and the vast majority of European campers use canister stoves. Or alcohol, which is also very popular there because it's quiet and clean-burning, both issues in the oft-crowded European campgrounds, vastly different to the pretty roomy campgrounds we're accustomed to here in the U.S.
As for which stove, most made today take a standard thread mount, so it's easy to find fuel. The Superfly ($50; www.msrcorp.com), for instance, works both with threaded fuel canisters as well as non-threaded ones such as those from Camping Gaz. So it would be an extremely good choice. The Primus Alpine Micro ($48; www.primusstoves.com) is another stove for which you'd easily find fuel. Switzerland is filthy with little outdoor stores, and you'll have absolutely no problem finding what you want. You might even just wait until you get there, then buy a European-design stove, such as the Primus, on the spot.