Good news Helen!
Your good taste in Microcars mirors that of my own, and for reason(s) never completely understood by myself,
allows you a purchase price likely not needing to exceed about 40% of what you would expect to need to pay for a base Messerschmitt or Isetta in equivalent condition.
So you may be able to afford one sooner than you think!
I should know, as during the last decade I ended up obtaining 2 and a half of them for about $11,000 USD total.
If you are living in the UK, you are especially blessed, as this is where they are the most plentiful and undervalued.
They use the same engine as a Messerschmitt, and have not too much too tricky about them, except for their plywood floor and perspex rear window.
So find one with a solid wood floor (pay particular attention to the area just inside the doors and also forward of the footwells) and your off to the races. Euphamistically speaking that is, as is common in the world of microcars, usable speed is limited to only about 45 m.p.h.