As a former 'trade-plater', who spent two and a half years hitching lifts, five days per week, I can tell you that the vast majority of lorry drivers won't give you lifts because it invalidates the vehicle's insurance if they carry anyone other than a company employee.
However, there are plenty of lift-sharing websites available:
http://www.liftshare.org/
http://www.nationalcarshare.co.uk/
http://www.freewheelers.com/
(For plenty more, just put 'lift share' into Google).
Chris