Oooh its quite important - I even had a list, and DH wasn't allowed to eat any of the 'labour-food' before I actually went into labour!
I think picky-ish/snacky food is easiest for labour, things that you can just nibble at rather than a whole baguette or something.. there isn't always the time!
I took great delight in going shopping and just buying anything that came in individual packets, or small pieces! Oh and foods that don't smell lots too!
Things like raisins, mini breadsticks, popcorn is good, nuts, crackers (Tuck/tuc biscuits are nice!), little biscuits. Cereal bars are really good. We didn't get anything like chocolate much to my disgust because we thought it might melt if it got particularly hot. Nothing that needs going in the fridge (i.e might go funny if warm) as you don't know how long you will be in there for. But anything small and snacky is brill. Oh and boiled sweets are good too if not hungry.
I'd even planned to get some nice bite-size bits from M&S, (
) cocktail sausages and pic-nicy bits like that, only DD1 was prem so ruined my plans!! Fortunately we'd stocked up on the above food items early.
I remember going into prem labour and freaking out - MW said we had a bit of time so sent DH home to get some stuff; I remember crying down the phone to him telling him not to forgot the food..
Do NOT forgot labour drinks - flavoured fizzy water is soooo good! You can get it in supermarkets, the big bottles for about 4 for £1.20 I think.