If you have opted to use Sage Pay as a Payment Gateway with BookingBug then you will need a Sage Pay Go Account. There are some technical questions in the application form, these answers should help you a bit..
Q: IP Address and Subnet Mask of server hosting checkout?
A: IP: 079.125.030.235 and Subnet Mask – 255.255.255.255
Q: Which type of service do you require?
A: VSP Direct
Q: Which Shopping Cart do you intend to use with your checkout?
Q: What type of hosting will you have serving your website and checkout?
A: Dedicated Hosting
We hope these help but should you have any further questions, please do not hesistate to contact us – firstname.lastname@example.org