SPIT,
Read the back of your ticket:
"Nor will the organisers be obliged to refund any entrance monies, should the event for which the ticket grants admission not take place or be curtailed."
However, the announcement on Airshow FM invited members of the public to send their tickets, along with a covering letter, to the Airshow Office at Waddington, where refunds will be considered. So, depending on how good your letter is, you may get refunded. Perhaps you could start you letter with:
Dear Airshow Organisers,
I'm not being a TIGHT A***, but £36 is £36
Good luck anyway.