Where can i buy seals for my sierra cosworth brake calipiers front and rear ?

GTStuning should do nicely

Brakes International sell em too.

http://www.brakesint.co.uk
http://www.brakepart.co.uk

Have dealt with them and they are very helpful, quick and easy to use.

Good luck!

I can second that, got seals and disks all round from brakes international - helpful, cheap, etc.