If you're planning to get hand on and maintain, a big positive that isn't in the manuals is to clean all the earth points for the electricals. This is one of the easiest jobs and most beneficial to a happy mini. I'd also suggest a very thorough steam clean of the car. Years of built up grease and grime will have covered everything.

Steam cleaning, uncovers grease nipples, identifies sources of leaks (and can create some), lightens the car, re-valcanises the surface of rubber, makes working on the car so much more enjoyable. You can see colour codes on wires, split boots and the list goes on. The temporary down side is the electrics getting wet. I would however argue it then becomes a positive as you will need to pull terminals to clean out any water and inspect and rejuvenate the connection.