The nearest airport to the Venue is Pisa.
Jet2 fly from Manchester on Mondays, Fridays and Saturdays.
Easyjet fly from Manchester every day of the week except Fridays.
Ryanair fly from Manchester on Mondays, Wednesdays & Fridays.
The journey from Pisa to the venue is roughly 35-40 minutes.
I'd recommend pre-booking a transfer or jump in a local taxi at the airport.
You may want to consider renting a car, there is not much around the venue so if you feel you want to explore the area and get some time away from the castle, booking a car is recommended.