Hi Kenmac,
Great to hear you have bought an LS400. I can now forgive any minor concerns Top Gear gave me..... Something good came out of it.
As Manc says the forums and club here are brilliant. Everyone will help you and there is piles of stuff especially on the american sites should you want to do some of your own servicing. I hope that you will enjoy the smoothness of the drive and all the electric goodies, especially the sound system, with its "Sizewell B" output amplifier.
They really can run forever. I've heard of 1 car in the US clocking up 600,000 miles, but if you keep the fluids in good order 1,000,000 is a fair target. I have done an 1800 mile fuel check, and am averaging 29.5 mpg overall, but the tracking was out so I hope to break 30 from now on.
Happy driving.
Rab