On Wednesday I saw my first film in 3D (Gravity) & IMAX. I last saw 3D films in the 1970's - they were b&w & rubbish. This one was amazingly good.
Gravity is rated 12A (although not in IMAX, only 3D) - does that mean that Ollie could see it as well as you & your mum? (there is certainly nothing in it that could harm his mind). It's well worth while; you would all be talking about it for hours afterwards.
Your nearest cinema is at Stevenage (17:45 showing).
http://www.cineworld.co.uk/whatson/6515?cinema=61&date=allCineworld Stevenage
Unit 4, Stevenage Leisure Park, Kings Way, Stevenage, SG1 2UA
(a good use for your £20 ??!!)
--------- Alex Kemp