If you don’t wish to carry your poster with you and would rather print it out in town, the nearest option is AVMG, a University print service (open to all) – you can email your poster in advance and collect.
£30 for A0 (landscape!) simple paper.
Email email@example.com (please arrange everything directly with them).
Address: AVMG, Department of PDN, Anatomy building, University of Cambridge, Downing Site, CB2 3DY. (This is 1.5 miles away, a half-hour walk)