Little devils

I'm surprised you still love them after all that

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I agree that, as they say: 'good fences make good neighbours'. All our march fences are now double fenced with hedging in between and the only time any sheep have ever got out has been when someone has left a gate open. Make sure the gaps between bars of the gate are not too far apart as lambs can get out between them. We have tied chicken wire to all our gates, and hang a stob by wires from the bottom rung to close the bottom gap.
Buffy, I don't think Wiltshire horns will be as athletic as Soays, but the fencing is still important.
If you are unfamiliar with sheep, I would recommend that you buy ewe lambs at about 4 months old when they are weaned. Ours are that age in August, but if your seller lambs earlier they will be available earlier. By buying lambs, you will have a while to learn about all the general management needs, and get to know them, before you have to go through lambing. I am not sure if Wiltshires are lambed at a year or as shearlings.
When we sell to new flock owners, we sometimes also sell them an in-lamb ewe, so they will have one experienced ewe to give them some lambs of their own early on, before their bought lambs are old enough to lamb themselves - many people like this and others would rather wait for an extra year to learn more slowly.
For equipment, the basics are; a shelter (simple home constructed with four sides and roof, low as sheep are not tall; water - this could be from a stream if you are lucky enough to have one, a water bucket refilled by you daily from a tap, or a gravity-feed drinker connected to a tap or rainweater collection barrel( agric suppliers stock these drinkers); hay feeder of some kind, depending on how many sheep you have.
www.iae.co.uk do good quality hay racks, troughs and hurdles and many agric merchants stock various makes. Some kind of catching system is essential - no matter how tame your sheep are, when you want to catch them they will not want to be caught. We use a simple set-up of a pen made of hurdles and direct the animals into it using electric netting, but not electrified, just set up as a big fishing net, with a wide scoop at one end, gradually closing the gap (against a fence) and the hurdle pen at the other. Foot shears - I find that the small ones which fit my hand easily and look like pruning shears are fairly useless - big sturdy ones with a slightly serrated edge suit both of us fine. Daggers to neaten the bum ends, and hand shears if you intend to shear them yourself.
For medecines such as wormers, anti-flystrike pour-ons, vaccines and so on, it's time enough to decide on those once you have your sheep - the breeder you buy from will give you advice and let you know if the lambs have been started on a vaccination programme or when they will need their next Crovect or Clik. I always advise new breeders to get to know their vets - a helpful vet will make all the difference. When we first started keeping 'funny' sheep about 15 years ago our vets thought we were mad but now they love our little sheep and one has this year started his own flock of Soays.
You will need hay for the winter - about 5 bales per sheep, and a little straw for bedding and you will need to feed concentrates in the winter, especially once you begin breeding - ask your breeder for advice on what she/he feeds hers/his.
I don't think you need any more equipment than this. Fancy things like dosing guns are not necessary for a small flock as you can buy individual plastic syringes for oral dosing, or with needles for injections, for a few pennies from your vet, and you will waste less product. Once you have your animals and you get used to handling them you will discover for yourself what you need beyond the basics, but don't spend money on stuff you may never need.