Yes you can do a charity flight without applying to the CAA. They issue a general circular (a white page), if you comply with the requirements then they do not want to hear from you. As I recall the requirements are: operate from a licensed/goverment aurfield, have > 100 hrs PIC, tyhe aircraft must have been certified by a licensed engineer in the last 60 days and all proceeds must go to a registerted charity. The exemption is there to permit this and encourage people to run charity flights. You canm find it on there web site under a search for 'Charity Flights'. Any problems pm me, otherwise enjoy the flying and the fact that you can help others make money from your hobbey .