As has been stated, food is not normally classified as a liquid but it's just possible that certain sandwich fillings might fall into the 'liquids' category. (My thinking is that toothpaste counts as a liquid, so perhaps peanut butter might also?).
Mascara and lipsticks are both definitely included within the 'liquids' category. Any liquids taken through security must be in containers of no more than 100ml. (NB: It's the size of the container that counts, not the actual amount of liquid inside it. You can't, for example, take a 200ml bottle of suntan lotion through, even though it's clearly less than half full).
All of your liquids have to be enclosed in a single, clear resealable plastic bag, no greater than about 20cm by 20cm. That's a single 'sandwich-sized' bag.
Pens and pencils seem to present no problem. I've usually got several in my flight bag and I've never been challenged.
Full information here:
http://www.direct.gov.uk/en/TravelAndTransport /Publictransport/AirtravelintheUK/DG_078179
Chris