Many thanks guys - got a quote from Warranty Direct and they were more expensive than Warranty Wise. I'm sure I could have haggled them down a little but I was quite taken by the endorsement Quentin Wilson gives to Warranty Wise and the general reviews I read of them on the internet, so I phoned up Warranty Wise to check out their cover and they offered almost £100 off the online quote !
Bargain ! Have gone for them - 25 months cover for £660, all mechanical and electrical components, £100 excess with dealer rates and additions for wear and tear, catalytic converter, air con and multimedia. I couldnt think of any other additions that I'd need - I checked to make sure the xenons, gearbox and MM were covered and they were, aside from that I couldn't think of anything else I wanted covered.
Incidentally - Lexus sent me a brochure with their Extended Warranty information and I was surprised at how much was excluded given it's cost and the fact that it's their own plan.