Here's the completed grid with all the answers filled in. The answers are also given next to the clues below.
2. Space station king makes love to 500 in forest - Mirkwood
3. Flee from the west and north with old letters? - Runes
5. He's a blob I confused with the main character - Bilbo
6. This noisy trading post would not wake student in disarray - Laketown
8. The chiefest of calamities re-worked as mug - Smaug
10. BO in broth, not right for small town - Hobbiton
13. The finder of the moon letters is a student/drone mix - Elrond
14. Go for a walk, but not south, to find a hungry monster - Troll
15. This dwarf was a sort of confused old blister - Balin
16. A skin-changer in part maybe, or not - Beorn
17. An inhabitant of the Misty Mountains may be boiling, but not I! - Goblin
18. Confused? I'll have the navy for look-out post - Ravenhill
1. Precious creature in Mogul student confusion? - Gollum
2. The lonely maintain, without artificial intelligence, the Open University is inside - Mountain
4. That place's old name was so Gareth! - Esgaroth
7. Head west with two rings, dig? Southern folk who imprisoned the dwarves - Woodelves
9. Staring fiercely around, the doctor showed the elven blade - Glamdring
11. One thousand and a 'alf? Wizard! - Gandalf
12. Having driven, turned to old measure to reveal the Last Homely House - Rivendell
14. North one staggered to find the leader of the dwarves - Thorin