Great to be chatting to hikers from Berlin, Henry

You can fly GLA/Campbeltown with BA from GBP28 each way in May and that would save ages compared trekking into Glasgow to catch a bus. Then you could buy your camping gaz in Campbeltown! It's the same airport – unless you're with Ryanair who fly to "Glasgow Prestwick" which is actually 30 miles away

Might be worth looking at connection times with your flight as I think there's only two flights a day (leaving GLA 0900 and 1630). Actually Glasgow is a great city to visit, and you could break your journey if you want to see it properly.
Hope to hear how you get on, regards, Jennie