I was clearly bored and wandering around the "My Account" section of my Lovefilm account and stumbled across a way of getting a further discount on my existing membership that I was not aware of so thought I'd share this deal.
Basically visit https://www.lovefilm.com/account/prepay.html
and choose to pre-pay for 3 months in advance and save 15% off normal membership and pay for 6 months in advance or more and save 16.67% off.
New members can obviously get a free trial and cashback but this is great for existing members looking to save money on their subscription.
Works for all package levels.