+1 for the Draper 30357 1/2" Square Drive 30 - 210Nm or 22.1-154.9lb-ft Ratchet Torque WrenchIdeally you really need two torque wrenches to cover all jobs on a car. A 1/4 inch will do the smaller fiddly stuff and the 1/2 inch the heavy duty stuff.
Draper 30357 came 2nd in the Autoexpress test £27.45 delivered . http://www.autoexpress.co.uk/accessories-tyres/84793/draper-30357
Screwfix stock Teng Torque wrenches at good prices
If you want a slightly smaller 3/8 wrench to cover smaller torque settings
http://www.ebay.co.uk/itm/DRAPER-54...537?pt=LH_DefaultDomain_3&hash=item51cb8bc039 £21 delivered