Ros, the only way to raise just lambs ie minus ewes for the table is to get orphan lambs in spring and bottle rear them, and slaughter them in the autumn. Bottlefed lambs don't always do as well as ewe fed lambs, so they might take a bit longer to finish. Lambs are usually only weaned a matter or weeks before they are ready for slaughter, unless they are primitive breeds like Shetlands. You might be able to get store lambs of some breeds in autumn maybe from hill breeds to fatten over the winter - some farmers do this as a business, but I woudln't liek to keep Blackface lambs in a garden unless it was awfully well fenced.
I saw your other posts about similar. I'm sure others will advise too.