"If it is not published somewhere easy to access then sending an email to the manager of the airport you intend to land at say a week before you intend to land is a reasonable amount of time ahead to expect an transparent cost.
If no response then refuse to pay any demand after."
As previously mentioned - Contact a Council, for information that should be readily available, can take from, many minutes (if extremely lucky) to several weeks, to get an informed answer.
The reality is you get past from one person to another, usually ending with a call back offer (that can take days to weeks to materialise) or delaying requests to put your enquiry in writing (I ask for a contact name to address the email to - more eqivacation).
The few Council Fee & Charges web pages, that I have accessed, are so complex that it may take quite some time, just to find the aviation section, which then requires deciphering (not always successful).
Your suggestion is fine for commercial aviation activities, that may be repeated over a significant period but not practical for most private/recreational pilots conducting "one off" trips, often at short notice due to weather & other considerations๐