Dear Mary,
1. Thank you very much for your / the letter which arrived / arriving a few days ago.
2. It was lovely to hear from you.
3. I am sorry I haven’t written (to you) for such a long time because I’ve been very busy.
4. As you know, we bought a new house in May.
5. It was in very bad condition and it needed a lot of work.
6. We have finished most of it now and it looks very nice.
7. John and I (have) decided to give a house-warming party on October 2nd
8. Do you think you will be able to come?
9. Please give me a ring and let me know if / whether you can make it.
10. I am really looking / really look forward to seeing you again.
Love, Bob.