Saturday morning cinema

Cineworld run Saturday morning films for kids at £1 per ticket:

http://www.cineworld.co.uk/

You're not supposed to take your own sweeties with you (now there's the catch!) but we've not seen them doing body searches on the door yet...

They also have a special offer for adults at £4 per ticket on a Tuesday.

Odeon Cinemas run Saturday morning screenings for kids at reduced prices for the children (£2.50 each) and parents go free (one adult per child):

http://www.odeon.co.uk/fanatic/kids/

Orange Wednesdays

If you buy an Orange phone (make sure it's a pay as you go) then you can take advantage of a two for one cinema tickets offer every Wednesday at cinemas all over the country:

http://www.orange.co.uk/film/orange_wednesdays.htm

In fact I've just noticed on another site that you don't even need to buy a phone to take advantage of the offer - all you need to do is register for a free SIM card: