Here's the completed grid with all the answers filled in. The answers are also given next to the clues below.
2. The great forest of Wilderland - Mirkwood
3. What sort of writing was on the map? - Runes
5. The hobbit's first name - Bilbo
6. Where the barrels went to - Laketown
8. The chiefest of calamities - Smaug
10. Mr Baggins' home town - Hobbiton
13. The finder of the moon letters - Elrond
14. Three of these wanted to eat the dwarves - Troll
15. The dwarves look-out man - Balin
16. The skin-changer - Beorn
17. Inhabitant of the Misty Mountains - Goblin
18. The look-out post on the side of the Mountain - Ravenhill
1. P'raps ye knows its name, precious? - Gollum
2. King under the what? - Mountain
4. The old name of the Lake Men's town - Esgaroth
7. The people who imprisoned the dwarves - Woodelves
9. The sword that isn't Orcrist or Sting! - Glamdring
11. The wizard - Gandalf
12. Where to find the Last Homely House - Rivendell
14. The leader of the dwarves - Thorin