If you liked your Ruby Reds you may also wish to consider the local sheep breed, then, being the delightful, canny, Exmoor Horn. Or, fairly local, the Dorsets (3 types - Poll, Horn and Down), all of which would give you a perfectly acceptable meat lamb. Portlands are not so geographically distant, either, are rare, beautiful meat and have beautiful fleeces you can sell to handspinners (if you treat them right - the fleeces, I mean!) Wiltshire Horn is only from over the border, too, and as I mentioned above, has the advantage of shedding its own fleece so being a little less of a worry on flystrike, plus not having to find a shearer for a small flock.
One decision is whether to breed your own replacements or not. If you do, then as others have said, you need a new tup every two years or he's onto his daughters - or, you can just buy a tup lamb each year, work him, then fitten him and sell him in the fat.
If you are happy to buy in replacement ewes, then you can use a tup of a different breed - a terminal sire like a Texel, for instance, or maybe a Dutch Texel (a bit smaller) if your ewes are a smaller breed themselves, eg., a Portland.
If you're planning to buy in replacements then you don't have to restrict yourself to pure breeds. You could buy Exmoor Mules locally (their mother is an Exmoor Horn and their father a Blue-faced Leicester) and run them with a Texel or Charollais tup for a good commercial lamb. Or, as SF is advocating, buy any reasonable commercial ewes sold as suitable for breeding, of mixed parentage but likely to produce good fat lambs to a Texel, Charollais or similar.
If your lambs are 'white' lambs (dad a Texel, Charollais or similar), then they should sell readily through your local mart. If you go the rare breed route, particularly if you breed true, then you probably want to be thinking about processing the lambs yourself and selling the meat. You'll get very little for a Shetland, Portland or Castlemilk Moorit wether in an auction ring, but the meat is beautiful and will sell readily as half a lamb - or half a hogget if you keep them through to their second year to mature - for the freezer.
Other breeds that I see smallholders praising include Zwartbles, Ryelands, Llanwenogs, Lleyns.
I see that you are wanting to start soon after the New Year, so you have little opportunity to go to shows and have a look at different breeds in order to choose one that appeals to you. One option would be to get some orphan lambs to rear this year, to get yourself used to sheep and give yourself time to choose your breed. Find a farmer you can trust to supply you with orphans that have had a proper start in life, though - if they haven't had colostrum, they just make work and usually heartache.