Hi there, just asked someone at work and he says yes, the only things you can't take through in Manchester is liquids (so don't buy a drink before you go through customs/checkin). He has said they are very fussy about size of hand luggage. No more than 16cm width. He also said terminal 3 has 2 cafes on the other side so you should be able to get a packaged sandwich that side anyway.
But like I said, he told me the restrictions are liquids only. He travelled from there last Saturday but a different terminal.