Photographic Paper Sizes

HI does anyone know where I can get paper in photographic sizes for printing on my Epson printer. I like to produce 10x8 inch prints but doing this on A4 wastes paper each time. I have looked at quite a few suppliers but they only seem to do the standard metric papers A4, A5, A3, etc. I'm in the UK and like Epson Premium Glossy although other paper surfaces would be interesting to try.

nn