Officate a wedding

Hi There, I have a general question. My best friend is getting married in 15 months and the couple asked if I could officiate. Now, I was honoured but looking at it in a practical sense, I have reservations. eg the course, costs and ongoing registration. Let alone the nerves about doing this right, without messing it up. Besides this isn't going to be a side career going forward. However, I'm keen to make it happen in some fashion or another. What is the bare minimum officiate input from a celebrant? Can myself and family to bulk of the vows and readings etc? Any advice would be helpful. Regards Angelo