A visa is required for both Irish and British passport holders.
Application at embassy in Harare:
Cost: US $50
Turnaround time: 48 hours
This was straightforward.
No carnet was requested. I was simply given a TIP valid for a month.
Departure was equally straightforward; get the form registered at the gate, take it to the office to be stamped, receive a copy and off you go.
COMESA or local 3rd party insurance required.
COMESA cost US $20 (paid in Z$ at rate of 1:1, so equivalent of US $5)
Valid for 30 days