The Cleckheaton Country is not really a quality specification, that is just what the pattern-writer chose and used. What you need is not something that is analogous to Cleckheaton in terms of quality etc., but the right weight/thickness.
8-ply wools are about 23 stitches per four inches (that is to give you the size of stitches, obviously a wool that makes 6 stitches over 4 inches creates larger stitches than a wool that fits 36 stitches into the same space of 4 inches, stitch size also depends on needle size and how tightly you knit).
Cleckheaton 8-ply recommends that it be knit at 22 stitches per 4 inches, typical of an 8-ply as I said. To choose a yarn/wool that matches, if you want to follow the pattern closely, you should buy a wool that is about the same. Wool labels should mention this, usually this is a little grid icon, underneath the grid will be something like ‘16 stitches and 22 rows/4in’. That means the manufacturer recommends this be knitted at that tension/stitch size.
So any wool whose label tension says approximately 22 stitches per 4in will fit: say from 20 to 24 stitches/4in. Ask the people at your favourite wool shop to help you find/choose/decide what is right, but it should be something about the same thickness (of course, if you find the perfect colour on sale but it is 19 st/4in, you might be happy with that).
You might also want to make sure the fibre content of the wool is the same or similar: synthetic or largely synthetic yarn doesn’t block, whereas yarn that is mostly natural fibre will. Cleckheaton 8-ply is mostly or all natural fibre (wool) - I forget exactly -, so you might want your choice of wool to match that and also be wool or mostly wool.
But your equivalent would be anything that is approximately 22 stitches/4in, and mostly wool (as opposed to acrylic/nylon/polyamide/other synthetics). In American weights, this would be about a ‘sport weight’ or ‘double knit’ wool/yarn. Just tell the people at your wool shop that you want about 22st/4in tension, and mostly natural fibre, and they will give you some options: you might want some nice soft cashmere for a bit extra money, or plain wool a bit cheaper, or soft merino in between, up to you: but the weight/thicknes of 22st/4in is really the most important thing.
If you want to think about it at home, check out yarndex.com: it is a reference database for all the big brands and types of wool, and will tell you fibre content (e.g. 80% wool, 20% nylon) and weight (e.g. sport weight) as well as tension (22st/4in) as well as show you the colour range.
You can browse Yarndex by weight/thickness: at the web page, click on the box that says ‘yarn weight’, you will get a pop-up box with different choices, click on DK (for double knit) and you will see a selection of similar weight wools. Any of these should be fine for what you want.