What are the running costs for a microlight in the UK?

Sharing of ownership is a good way to save money. It is a comprimise in that you are sharing with others. Write a contract of ownership stipulating who is responsible for maint. and other duties.

I have found that a retired week day pilot blends well with a working weekend pilot. An instructor is not a good partner; he will beat up the plane with students, however, an instructor is good for insurance purposes. A mechanic is a good addition, and he should be given free flight privileges for maint purposes.

The ideal number of owners could be anywhere from 5-10. Flying clubs were traditionally based on 10 per plane. That may be a bit too much, but there are always the few who don't fly much. I flew in a flying club where I could drop in at the airport any time and fly without reservations made. We had three planes.

The key advantage of having several owners is that you all could afford hangar space, suitable maintenance and upgrade costs, and the cost of insurance, etc.