"Va a haber mucha comida en la fiesta."
Translation:There is going to be a lot of food at the party.
Hay is the conjugated form of haber. Remember that the ir+a+infinitive structure means "will be". Simply using "va" doesn't indicate a future action.
Va a haber = There is going to be / there will be.
"much" doesn't generally work with collective nouns in English, except in the negative (there isn't much food) or after an adverb (there is SO much food).
Otherwise you'd always say "there is A LOT of food".