Rather than listing all individually and taking up loads of threads will list some in 1st post. Code will work on all over £50 and can be collected in store with Clubcard Points as well.
The one in the direct link seems a good buy with decent reviews but others might be more appropriate or better value.
PS - Code will work with anything on site over £50 - If something priced at between £45-£49.99 just add a cheap item at £1.00 eg, sim card to take over £50 and apply code.
Possible Quidco also available.