The Darksword minis are cool for charachters, but are a bit more expensive and large than most. For mass battle there are alot of possibles in Historial and fantasy ranges
Here's a couple of discussions of such.
As well as sources, there's a few interesting kitbash/mixing suggestions here:
http://theminiaturespage.com/boards/msg.mv?id=269232
Specifically about 15mm forces, but lots of historical compairsons.
http://theminiaturespage.com/boards/msg.mv?id=263355
A big one:
http://theminiaturespage.com/boards/msg.mv?id=233217
Though as the
OP points out, many
LoTR figs could work, some folks might be a bit confused seeing the mixing of the two fantasy universes.
I'm a pretty dedicated 28mm gamer, but if I were going to try GoThrones gaming, I'd want to go large in scale, probably with 15mm figs to be able to play larger battles.