Want to keep the interior nice? Use a car cover in the sun whenever you can or a least one of those aluminum covered cardboard window covers in the front window.
The sun BAKES these cars and I've seen Lotus dashboards on "Rent-A-Lotus" vehicles completely faded and melted.
That and some Zymol Leather conditioner for the seats and the door panels and your interior is fine.
Exterior?
Keep a spray bottle of water in the trunk and a couple rags and wipe off that gunk on the body near the rear wheels after every drive.
Wax is a must...whatever you like. I like the Zymol wax but everybody on LotusTalk has a different opinion.
Wash the wheels with a hose, then wipe them off. Most of that brake dust comes off with paper towels.
Avoid wiping the edges of the Starshield too much.
Wash it yourself. Takes no time at all and is part of the fun of owning a Lotus.
P.S. If you gotta get product, Griots is ok.