Congratulations!
First ride is always very exciting. My first ride I didn't even have the doors or windshield in. Second ride, still no doors, but very little turbulence in the cockpit at 80 mph!
Plug colour is not a reliable indiction of whether then mixture is correct. I really recommend using an Air/Fuel ratio gauge: no goes work, no surprises.
Lotus Europas are 98% cars. The last 2% you are always working on. You're successful so the 2%n is always changing. Sometimes it's a necessary (light bulb, wipers, etc), sometime just a want (better ventilation, extra lights, etc) but there is always something left to do. I like that myself. Makes the car more engaging, and the connection interesting and personal.