Hello Linda and thank you for "painting the picture and giving it a frame" to enable us to respond.
I see that you have had some really helpful suggestions already. Members really do try to be helpful where and when they can. From memory Nic, Neil and Bob are particularly helpful and knowledgeable about SC430 matters.
The first thing for me to say is that given you have bought from a Dealer, you have Statutory Rights and he has Statutory Responsibilities.
If the car develops significant problems within 6 months of purchase then it is the Sellers responsibility at Law to put matters right at no cost to you. The Law deems that such problems were present or were developing at the point of Sale. What is or is not significant has to be determined according to the facts of each case.
It is my view that a M.O.T. Certificate would not have been issued if your car showed signs of significant matters, thus the two matters you mention would not warrant asking the Seller to repair or replace at his cost. That is not to say that you should not approach him and suggest that he might like to make a contribution..I leave that to you.
As far as ongoing maintenance and servicing is concerned, you have three options.One, a Main Lexus Dealer, Two, a local Toyota Dealer and three, a local Independent (Indie) who is knowledgeable about Lexus and/or Toyota.
A Lexus Dealer will be expensive,but if you talk to Lexus at Milton Keynes or Lexus at Hatfield, they should inform you of their preferential rates for older cars such as yours.
A Toyota Dealer will be less expensive and an Indie will be even less expensive and if you can find a good one then he will be worth more than his weight in Gold to you. I attach a list of "Garages" which Members have used with satisfaction and there may be one or two near to you that you can talk to. These are not recommendations from me or this Forum.They are simply organisations with which Members have been satisfied.
I hope that I have been helpful and that you enjoy many years of Lexus satisfaction.
Lexus Indie Garages (1).docx