Instructions:£5 off £20 when using the order and collect (ordering via the catalogue like you do in Argos) in the new Tesco homestore in Cribbs Causeway.. Expiry date was 3rd or 5th August - can't quite remember. No actual voucher required.
I guess it's most valuable if you are buying a low value item on sale. I presume this is to kickstart their catalogue shopping division. Should Argos be fretting?