You can write to the CAA and ask for permission if you do not fall within the AIC. I tried it when I had about 120 hours P1 and permission was refused. If you are close to 200 hours you may have more luck. I am not sure what their attitude is to Permit aircraft (the Bucker Jungmann which recently crashed with a fatality was apparently doing charity flights and that was on a permit, so it may be possible to get consent).
You must clarify the position with your insurers and if necessary get an amendment to your police. I am not sure if standard policy wording covers charity flights.
You can only try!