Regarding the Halfords pro guarantee, every single I've taken back has been swapped without receipt and without question. I've taken back a couple of snapped sockets (after I hammered them onto the wrong size heads deliberately) and I even ground down the 8mm hex to use as a hub spreader tool, and they swapped that too!!
Best decision i made to buy the Halfords 150 piece set. Great value for money Dont know anyone that has had a problem with taking bits back.. but then again it helps having a mate who works there..
I just brought this socket set a few weeks ago, being the cheap skate that I am, I went for the socket set that contains as many of the bits/sockets that are required for VW cars. Inc 7mm allen key (caliper bolt) and 24mm socket (mk3 steering wheel).This set from some mr no brand, linky was only 30 delivered and is has been alright so far, done my brakes and general body work.