I would apply for both an FAC and SGC at the same time, which if done together is £60.
You don't need to have previous experience or a reason to obtain a shotgun certificate so that's out of the way, with the FAC, you have the land to shoot on and "Good Reason" to possess a firearm capable of dispatching rabbits, pigeons and foxes. Experience is not a prerequisite of being granted an FAC but it obviously helps, ultimately if you have the land and reason, they cannot refuse you, unless there are secondary issues about your suitability of course.
Calibres, well Shotgun in 12 bore, .22LR