Prices seem to be a little cheaper here in Suffolk:
https://www.cineworld.co.uk/magnoliaPublic/dam/jcr:0192df05-683c-4908-b719-4c707d30f1d3
Also, if you sign up to a year's contract, you can watch unlimited movies for just £17.90 per month.
For comparison . . .
A match day ticket to watch Arsenal will cost you £97.
A ticket to watch our local non-league football team will cost you a tenner.
To hear a cello recital, given by a solo musician, sitting on hard pews in our local church costs £15.
West End Theatre tickets typically cost £60 to £100.
Local theatres often charge about £40 to £60 for professional productions.
Concerts given by pop stars often cost £80 to £120 for a ticket.
Tickets to the F1 Grand Prix at Silverstone start from £155 but a seat in a stand costs between £200 and £400.
£18.50 to go to the cinema doesn't sound particularly outrageous to me!