Both sentences are correct,
Something to understand - Will which is implied with (I'll - I Will) is a modal verb and requires another verb to make sense - example I will do/ I'll do homework -vs- I will homework / I'll homework
i'll (I will) do - refers to a present/future action that occurs alongside another - for example "I'll do the washing while I wait for the postman"
i'll (I will) be doing - refers to a future action such as - I am unable to meet you later as I'll be doing my homework.
So in short, "do" suggests present, "doing" suggests future
Hope it helps :)