...where do you get 'non flammable interfaces' from...
They are readily available for both candles and tea lights. For candles, search for "Candle cups", most of the good UK turning supplies businesses sell them and prices vary considerably, but once you start finding them and getting into the terminology, you'll be able to widen your search onto internet auction sites etc.
For larger candle stands; for candles of a few inches diameter, I use plain slate coasters or metal disks. Again, a search of ebay found me a supplier of brass, copper and aluminium disks in all sorts of diameters. I've made several alter candle sticks for churches, and they like to be able to carry the candles stick, with burning candle, for various services, so I insert a 50mm-long piece of 50mm i/d pipe into the top of the candlestick, this holds the candle quite safely.....and has a 50mm diameter metal disk glued into the bottom of the recess in case a candle is ever allowed to burn right down.
For tea lights, again try the main suppliers of wood turning accessories. Ikea used to do a product called "Glimmer", which was available in its thousands, so there was always people selling them on in tens or hundreds, but Ikea no longer do them and the supply seems to be running out.
There is a business called Candle Cavern
http://www.candlecavern.co.uk/shop/candle-accessories/candle-holders which sells some good quality candle spikes for larger candles, and I'm sure there's plenty more suppliers if you search thoroughly.
Les