Here’s the completed conversation using "shall," "will," or the correct form of "be going to":

A: Your garden needs tidying.
B: I know **I will** do it this afternoon.
A: **Shall** I lend you my gardening tools?
B: Thank you! **I am going to** come round to collect them later.
A: **I am going to** visit my brother this afternoon, so **I will** bring them to you now if you like.