I have used embossed styrene sheet tiles for all the roofs to date.
I have been very happy with the effect .... until now because (a) all the roofs are beginning to look the same (b) the thickness of each tile looks overscale (which has never bothered me before but is starting to - a worrying sign - next I'll be worrying about loco running numbers and head codes) and (c) the pattern is repetitive (which is my fault because I should have built in the odd broken or dislodged slate).
However, on Lee's lnr model making blog he shows a very effective technique for home made tiles using slightly textured wallpaper.
Since my blog is in part to record the things I learn and in part to share with fellow new modellers those things (on the off chance any read this), I am unembarrassed to say that this is a revelation to me, although I am now reminded that I saw Geoff Taylor do something similar on his DVD.
Anyway, I think it's brilliant and I am going to try it for the chapel.