There's no Netflix in the UK, just Lovefilm and a range of others including Blockbuster and Amazon. From the sounds of it, they're definitely the UK-Netflix equivalent. Netflix did plan to launch a UK service in 2005 but pulled out to concentrate on the US market.
I've been with Lovefilm since it was ScreenSelect, back in 2003 and can recommend it. Quick turnaround, lots of titles and helpful staff when you get the odd scratched disc. They send you a fair few adverts/leaflets with your rentals and are always trying to get you to sign other people up but that stuff's easy to ignore if you're not interested.
They've been accused of "throttling" whereby they balance out high and low use customers by slowing down certain transactions, but as a high use customer on their highest price plan who routinely sends titles back the same day, I can say I haven't really experienced that at all. The quality of service will mostly depend on the reliability of the postal system in your area.