Before you think about ewes and lambs, are you able to give them proper care at lambing time? If the land is a distance from your house, would you be able to stay on the land, or how would you manage?
Definitely a good idea to start with store lambs even if you eventually want to breed your own. You will learn basic sheep handling and care without anything like as much stress
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Your choices are to fatten stores over summer and let the field rest over winter - by far the easiest, and the ground would take more at a time this way. Or buy lambs that will need overwintering and fatten in spring, in which case you would want less heads. But the lambs would be cheaper to buy.
If you can get good Texel-type store lambs they should finish on grass by October. If they’re not ready by then you’d need to give them a little cake - half a pound of coarse mix a day each, max, to keep the condition on them. Or let them lose condition over the winter and regain it on the spring grass.
Cheviot types are likely to need longer, into the New Year, but will be bigger when they do fitten. They’ll manage on grass or hay. I’m not sure if you’d find anything of that type where you are, and they’re usually sold in big batches.
I’ve no personal experience of Suffolk types, but the tend to be lambed earlier so should fatten before winter, I imagine. And they make heavier carcasses than Texels.
Swaledale wethers or mule wethers would make fab meat next summer.