If you want to hire it on your own for 1-2 days, expect to be very limited in the amount of miles they'll let you cover. There will also be a huge excess for any damage, which is very easily done in a wide, low LHD car on narrow roads. It's unlikely to be covered by a traditional hire car excess insurance, so if they find damage during the return inspection, you're going to have to just pay up.
I used to work for a company in Monaco who offered a similar service, but it was 390EUR per hour, and you had to have the instructor sitting in the car with you, which obviously is a deal breaker for a lot of people. We did however offer 0 excess, with everything included in the upfront price, and no mileage limits. I heard a lot of horror stories from people who'd hired one on their own in the past, and been stung with huge excess charges for minor damage, which personally would put me off doing it myself.
IIRC, you can rent things like F Types from big international companies like Hertz and Avis, I think I'd prefer to do that than risk an independent supercar hire company. I know it's not quite the same experience as a Ferrari, but there's a lot less risk of something going wrong, and if it does, you stand to lose a lot less money.
