Right, so had the car two days now.
First day hardly touched it.
Today, took it to dealership, got waterpump and cambelt changed as well as a new boot badge put on
Had a Panda courtesy car, lol.
At same time they gave it a full health check; nothing wrong with it full stop that they can see. That ties in with the MOT pass with no advisories too.
That buzz in the cabin was from the little unit on the roof that houses the alarm. I pulled it out, padded it around the edges with kitchen roll, then refitted it. Buzz gone.
Took it for a nice drive to the in-laws and back cross-country; averaged 49.9mpg according to the computer. Tank range of ~700 miles.
The in-laws cooed over it. "Oooh, leather! Blimey, six gears! Crikey, what a big boot!"
Gonna enjoy this car.