Here are the answers filled in with the correct tense:
a) I'm very tired. I think I am going to bed. b) The school orchestra is performing in Berlin this weekend. c) Sally, we've got no bread left. - OK, I will buy some. d) Hurry up! The train is arriving in half an hour. e) Let's stay at home. I'm afraid it is going to rain. f) Have you got any plans for the weekend? - Yes, I am visiting my granny. g) Can you help me, please? I can't finish the project myself. h) Have you bought the tickets? - Not yet. I will do it tomorrow.