The vast majority of aircraft are kept outside, whether it's an Airbus or a Cessna 172. There are a few locations, mostly very exposed to bad weather, where it is cost-effective to hangar aircraft. Most fabric-covered aircraft deteriorate quickly when left outside, so it is cheaper to pay the considerable cost of hangarage. Typically, in the London area, hangarage can be up to £5,000 a year for a single engine aircraft, though cheaper in more rural area. At most GA airfields, you will see rows and rows of aircraft such as Pipers and Cessnas tied down outside, with maybe 10 or 20 vintage types in the hangar.
Hanagarge is rarely available by the day (or night) as most hangars are full with a waiting list. You might get lucky if a based hangared aircraft is away and the hangar operator is prepared to accommodate you, but don't depend upon it. When touring abroad in a metal aircraft like a Piper or Cessna, be prepared to tie down overnight. Most aircraft are equipped with special rings under the wings, at known hard points, to which straps can be attached to blocks in the ground.
TOO