Check with your bank, some accounts offer 'free' mobile phone insurance.
I thought about getting the Lloyds TSB Gold service account, the
mobile phone insurance being a major advantage for me.
However when reading their T&Cs for the mobile phone insurance it
transpires that it doesn't cover you if your phone is 'lost', only if
it is 'stolen' or 'damaged'. Also there's an excess of £50 per claim
methinks.
I've also had the Orange insurance on a Pay as you Go phone I keep for
visiting family, however I've cancelled that one as the premium of £50
pa seems a bit steep (although no excess if you claim, and 'lost' is
covered).