Hand luggage is definitly allowed now, if you type in http://www.lbia.co.uk (Not just trying to plug LBA ), the first page has a long list with all the regulations.

Food

• Sandwiches • Crisps • Fruit • Vegetables • Other solid foods • Writing Implements • Biros • Pencils • Fountain pens with single open cartridge in use • Baby Milk / Food • Empty containers such as empty bottles, beakers or flasks • Baby Milk / Water / Juice / Paste Form Food (if tasted by the passenger) • Baby Food Powder

Ive never tried eating writing implements, biros, pencisl or fountain pens!