there are many screen printers here in uk. however they are all different .. prices, min order, turnaround, inks ..
as far as i know there are ..
I DRESS MYSELF The eco-friendly screen printer - they are printing only with water based inks and i think they will be able to print max 4 colours.
T Shirt Printing | Screen Printing and Embroidery Services - October.co.uk - i heard that they are very experienced and professional.
www.monsterpress.co.uk - dont know anything about them, but they printed a lot of t shirts.
Welcome to White Duck Screen Print | White Duck Screen Print - 01225 481 696 - ...
Fifth Column t-shirt printing | Fifth Column - they are very experienced and based in london.
it's just a few what comes in my mind straight .. dont know if anyone of them would like to work with start up companies. from my experience .. usually big companies dont care much about small business. i would suggest to find small companies who would be interested to invest some time and help you out to print.