What aircraft?
Crossing the Alps (which you would not be doing if just going UK-Switzerland) is easy enough if you can go to ~FL130 and go straight over the top, picking a nice low wind clear day for it. Great scenery. But that needs oxygen, which is perhaps why most people going that way fly in the canyons ("mountain flying") and then one only needs to cross the spine of the Alps range which I think can be done at about 9000ft.
Switzerland is GA friendly, with lots of airports. The usual things to watch for are Customs and PPR.