Hi Nick and welcome to the LOC.
I too use Lexus, Cardiff. Natalie and Charlotte on Service Reception are fantastic.
I bought my first IS250 two years ago, it had a full service history but with the last two services done by an independent. After an inspection, they accepted the vehicle for the Lexus Warranty.
Had my present IS250C for a year now. I bought it from an independent trader in Southport and it had a full Lexus service history from Lexus Manchester. It was accepted for two years warranty without inspection. Since then I've had a replacement headlamp assembly (water ingress and condensation) and a replacement rear caliper (seized)just last month. My claims roughly equate to the premium and I have another twelve months to run, that doesn't take into account the AA premium cover too !
It is dependent upon you having your CT serviced at Lexus. You should be able to start it after the twelve months dealer guarantee. I'd organise it now if I was you as the price could rise substantially, the present deal is based on 2 years for the price of 1.
Yes, the premium is payable over 10 months interest free.
As "royoftherovers" says...."A NO BRAINER"