I recently bought some lenses from Get Lenses and they seemed the cheapest I could find. They have also given me a discount code for friend / family so if anyone wears contacts and wants 10% discount then PM me. You would need to be a different prescription to me though, mine is +4
Also if you joined the cash back site I use you may even be able to swing another 10% off that order
http://www.quidco.com/user/641461/
Since I have been with Quidco I have had nearly £600 in cash back from things like insurance and mobile phones. You don't even need to follow my referral link for the cash back site, just look it up and join anyway, just that I would get £2.50 if you followed my link and earns cash back.