hmm.. piwlady, i'm pretty sure that naze was first on using those glow models with lava (in this pic:
http://www.hiveworkshop.com/forums/attachments/terrain-board-267/39967d1223774386-nazes-terrain-showcase-burning-land-edited.jpg).
Your mine terrain is great though.
About the terrain, first of all, i'd say you've got to define a colour scale.
Right now, you are mixing cold blue, warm red, and a pretty vivid green together with that brownish stuff.
I'd say, pick doodads that fit together, browse among the collumns in the UTM, and try to match most colours. If they doodad is nice but the colour is wrong, try giving it a slight tint.
Red is ofcourse the natural colour for lava, but it also gives a shine onto nearby surfaces - something that the glow is supposed to provide. Therefore it just looks awful having that contrasting green right next to it. You could have a dark, blackish soot-like tile in the immediate areas around the lava for a nice effect, but that is not neccesary when you're dealing with stone tiles.
Also, try looking at images of some real cathedrals; they oftenly have arches along the sides with collumns inbetween like in this shot:
http://fc03.deviantart.net/fs19/f/2007/267/d/b/Abandoned_Gothic_Cathedral_by_I_NetGraFX.jpg