MOD insurance rules have changed. As far a I understand Crown Indemnity on your insurance now means nothing. Unless you have a waiver certificate you will be charged £20 per visit. The waiver certificates cost around £150, irrespective of your own insurance and is valid at all MOD sites. Any old waivers (issued on proof of Crown indemnity) are valid until they expire, replacements will be as above.
Landing Fees are separate payable in addition to insurance fees.