I have NF, they are prone to EMS as they have evolved to live on sparse grazing and like most natives do not need a lot of hard feed. I feed my Highland and Connemara youngstock a good stud balancer, with Baileys they have a formula so you can replace with stud mix if needed, or D&H Suregrow which is cheaper, but the majority of their diet is hay. Some of the balancers are formulated for TB's so check the bag, it will say native or warmblood as both need slow steady growth.
NF are tough compact ponies, if has been bred on the forest it will not see a hedge as a barrier and will walk through a thin one. They will just about eat and edible weed or thistle, if the thistle is very tough if you knock it down they will eat it, and they eat nettles as well.