Do you just mean a sheet of A3 card? Look in your phone book for stationary printers, who generally operate on a 2-colour press. Regarding paper quality - do you want it poster standard (170-200gsm) or light card (250-300gsm).
If you're in West Yorkshire, I have used AW Angus in Leeds in the past if not - just phone a printer (an independent, not printing.com/kallkwik/prontaprint etc) and ask for their advice. Most independents are fairly specialised and will pass on work where it's not worth there while (and in most cases, to be frank, your job won't be)