may depand on what you are flying..( fixed or rotary ),...where you are flying...and how much you are flying ( of either )...
it may even depend on your level of experience and what sort of risk you are considered. i think on one occasion i was not charged anything for recreational flying..but that was some years back. i think i am charged a loading now but to be honest i cannot recall how much nor on which policy even to check and give you some idea.
one way or another, it will probably be used to get some more money out of your pocket..
however best to declare it and take it on the chin ( or threaten to change insurers )..no point in having cover..thinking your missus and kids are covered..if after you have blasted off they find the insurers renage on the policy/ies due to lack of disclosure.
ask for a quotation warts and all.
its the only way. good luck and safe flying..
the dean.