Situation is - we had an old back boiler ripped out and replaced with a
combi in another room (please do not treat statement as a troll....)

There is now a reasonable sized hole in the corner of our front room which I
would like to put a basket gas fire in (plumber is ok with flue, room
dimensions etc so thats not a worry)

Basically I need something slightly decorative to put in back and sides of
fireplace to tidy it all up and protect what I believe to be normal bricks
towards the back of the fireplace.

Given the dimensions of it all, putting in firebricks is just about possbile
but undesirable to to relative thickness and the 'buff' colour most seem to
be. I dont' want to start taking too much of the old brickwork out and
fiddling as I'm not an experienced builder and don't fancy the whole chimney
stack on my head.

I'm guessing most glazed tiles would get damaged by heat, even if there is a
couple of inches clearance between fire and tiles. Quarry tiles might
survive it but its not very appealing visually.

Os what I'm now looking at doing is possible going for 1cm thick unglazed
slate tiles on top of a good thick layer of limed mortar - anyone know how
good these are in repeated exposure to heat? Failing that I might try
trawling round a few stonemerchants for basalt based thin tile-shaped
stonework.

The plumber also said you can get some sort of heat resistant plasterboard,
but I've yet to find any in the sheds.

Anyone had experience of this sort of thing?