How many holes would you expect a golf buggy to last?

Having done the Macmillan challenge several times, I was more than happy to stop after each eighteen, lunch after 36 holes (and a change of shoes and socks). However if the OP wants to encourage non-golfing friends to help raise money then where's the harm.

The courses I've played (not always my home course) have given us right of way and one even had the marshal regularly going ahead, particularly in the afternoon to ensure we weren't held up. It makes sense especially the the course is likely to be busy. Good luck to the OP (and anyone else) doing it and I hope you raise plenty of cash