First thing - beware of 'good will' agreements such as 'I'll graze my sheep/horses/cattle on your land and in return I'll cut your hedges'. There's a reason many legal agricultural agreements are for a day short of a year so nobody gets grandfather rights on your land. You are right that children and tups absolutely do not mix, so now is the time to stop that agreement. That leaves the problem of who is going to cut your hedges, but wildlife hedges are cut only once every three years in rotation nowadays so they can become taller and bushier for nesting birds. What you really don't want is someone else having an influence on how you manage your land because you will have your way and they will have theirs. If you have someone else's animals on your land you have no control of how they worm them or their general welfare, which can become a bone of contention.
We had problems when we
bought a field from a neighbour who thought he could still tell us how to use it, forbid us to remove a gate, forbid us to plant a hedge, drive his tractor through it and so on, and this was someone with whom we were friends, so we thought!
Just tell the chap with the tups that you're sorry but you have other plans for the land.
For the paddocks, you will be almost certain to get a few animals eventually, but take your time to decide. This will give your land a year or two to clear itself of any parasites from the tups which have been grazing it (incidentally free range hens are good at clearing herbivore worms from pasture and hens are great for children to start with)
Grass which has been left to grow long in the summer is wonderful for children to run and roll about in, with a lovely variety of grass seed heads blowing in the wind, depending on the original mix sown - not every meadow has flowers.
Machinery - you will end up buying some, perhaps a tractor and hay mower, a hedging attachment or you could get a thing called an Allen scythe which is a small powered implement with a cutter bar at the front which you walk behind and it can deal with long grass, brambles, nettles and so on. Long grass only needs cutting once a year, paths as often as you would cut your lawn.
My advice is not to take any major decisions quickly. Take a year to learn about your land, where it's wet, where it's dry, which way the worst winds blow, frost pockets, where the thistles are, if there are any wild flowers which appear when you leave the grass uncut, what the soil is like and where would be best to grow veggies, which areas are shaded/sheltered by the woodland, where past owners have dumped their rubbish to make a no-go area. You will be able to experience the local climate for a full year which will give you some idea of whether you can look forward to sunshine, rain, snow, high winds and so on.
As I mentioned you will be almost certain to get a few animals at some point, if only for the children, but take your time, don't rush in and get some of everything, as 3 acres is not much ground once animals are involved.
I can't advise on a wildflower meadow as mine hasn't really worked out
but many meadow mixes are generic, whereas once you have your own land you are likely to want wild flowers local to your area.