I'm a cynical barsteward at times, and often look-on at people having a nice year-long jolly - cycling round Africa or walking round Britain or, indeed, undertaking some exciting activity Smashy & Nicey style - for charidee - and wondered "is this more for you than them?".

Well here it is: jumping out of a perfectly good aircraft for the NHS costs them nearly £14 for every £1 they get. Proper peer-reviewed paper -

Parachuting for charity: is it worth the money? A 5-year audit of parachute injuries in Tayside and the cost to the NHS.
Lee CT, Williams P, Hadden WA.

Abstract
All parachute injuries from two local parachute centres over a 5-year period were analysed. Of 174 patients with injuries of varying severity, 94% were first-time charity-parachutists. The injury rate in charity-parachutists was 11% at an average cost of 3751 Pounds per casualty. Sixty-three percent of casualties who were charity-parachutists required hospital admission, representing a serious injury rate of 7%, at an average cost of 5781 Pounds per patient. The amount raised per person for charity was 30 Pounds. Each pound raised for charity cost the NHS 13.75 Pounds in return. Parachuting for charity costs more money than it raises, carries a high risk of serious personal injury and places a significant burden on health resources.
https://www.ncbi.nlm.nih.gov/pubmed/10476298

Don't do it folks.