Remember if you have something in place and used 'a bit' then after 10yrs you have right to planning permission via default.
There can be one 'fly in the ointment'. The planners will give you permission based on the previous level of movements. You have to prove how many takeoffs and landings you have made. Then they work out the average and give you that level of movements.
So if you can 'prove' an average of 300 per year they will give you one movement per day. This cannot be carried forward if you don't use it. This can restrict whether you can have a friend or two over as the NIMBYs will be counting movements and will report any infringement.