Can someone please tell me what cable I would need to link my laptop to a larger tv screen, is it HDMI or would a USB do the same job?
HDMI probably but only you know what video outputs the laptop has and, for that matter, what inputs the telly has- Display Port and VGA are other less likely possibilities. Depending on the form factor of the laptop the hypothetical output may be mini-HDMI which will connect directly to full sized HDMI with the right cable but does look different- that might explain the question I suppose.
HDMI is a safe bet usually. I got a monitor with NvidiaSync and it required a DisplayPort cable to activate. I had to get a mini DP to DP cable to get it working.