Ours don't jump

. Our march fencing is pretty secure though just in case, with a double row of stob and mesh 2 or 3 m apart and a hedge growing in between. They don't jump into the hedge to graze it, or go through it (although in the past Jacobs have). Between paddocks, we use single stob and mesh fencing, but with an extra strained plain wire on the top (ie two). I hate barbed wire with a vengeance - it doesn't stop animals from jumping but rips their bellies when they do, not to mention human hands etc.
The exception to the 'they don't jump' claim is when you are penning them, so an extra tall fence there could be worth it, maybe deer stobs with two lengths of mesh one above the other if your flock is a wild one.
The mesh we use is the slightly taller type - not sure of the exact height, but it's one which is readily for sale. It's best to go for a nice sturdy mesh, not the cheaper flimsy stuff, because when you have a tup he could well use it as a head scratcher and the weaker stuff won't stand up to that.
Well strained high tensile wires are an option, but certainly won't keep lambs in. The downside of mesh is that the lambs go through a stage when they can get their heads stuck. I suppose it depends on how much it matters if they escape and wander around your holding.
The slope - if it very steeply sloping then this would be where they would choose to jump if they're going to, jumping from higher to lower. A few extra top wires at that point would solve it.
Great choice of breed