Well, got the following reply to my email -
Hello,
Thank you for contacting London 2012 about your dietary requirements.
Medication and needles are permitted through London 2012 venue security, provided they are required for valid medical reasons, For details of what you can and can't bring into venues, including water and other liquids, go to london2012.com
Kind regards,
David
Not terribly helpful! However on my spectator guide (thanks for pointing that out Tina) it points out a security link, where it tells you what you can and can't take - if I had a baby with me I could take in a litre bottle of water, but if I am taking lucozade I will have to take it in up to 10 x 100ml containers! no part filled larger containers are permitted. And as you say I can take food providing it is not 'excessive'.
Well I suppose I can't really complain, that should work - it's no different from a lot of venues. Thanks everyone for your help and support.