Characterisation of Lucas North
Lucas North is an insecure character, who wants to fit in and show his abilities and fitness to be taken seriously in his profession and by his peers, a veneer he wants to hide behind. He demands the highest from himself, but internally fears, that he won't be able to meet the demands put on him by his job and others, because of his background, because of his upbringing, because of his time spent in a Russian prison (and as the last episode of Spooks 9 also suggests) because of all his lies of and in his life he tried so hard to hide.
Food suggestion for Lucas North
Carpaccio (Original version developed by Giuseppe Cipriani in Venice) - with white bread and an excellent vintage Italian red wine - (Heeding the current Italian food appreciation in the U.K., while still fitting his desire for rawness and immediacy).
Later to relax, his time in Russia would come out and show in his further choice:
Russian caviar - champagne (vodca would be too disabling for an agent and Lucas North has too much style to drug himself senselessly). Russian blini as a sweet dessert.
Lucas North, as pale as he is, does not seem to me as an entirely healthy or health oriented man. So vegetables are out of the question for him.