UK suppliers organise their pottery glazes by firing range first and by finish second, which is the same order a buyer should use. Within that, most stock a house range plus one or two named brands, and the differences between them matter far less than the difference between a glaze that fits your body and one that does not.
How a UK glaze range is organised
Earthenware glazes, stoneware glazes, and then the sub-groups: transparent and white, plain matt, coloured gloss, reactive and speciality. Brush-on ranges are usually listed separately from dipping glazes because they are formulated differently. CTM's price list shows exactly this structure, with earthenware and stoneware glaze groups listed apart.
House ranges and branded ranges
Most suppliers sell both their own or a manufacturer's bulk range and one or two imported brand ranges in small jars. The bulk ranges are what a studio glazes with; the branded jars are what decoration is done with. Buying a jar of a branded colour to try before committing to a bucket of anything is the cheapest research in ceramics.
What to check before ordering
The firing range against your clay and kiln. Whether the product is a dipping or a brushing glaze, because using one as the other gives poor results. Whether it is supplied wet or dry, since a dry glaze needs mixing and a wet one is heavier to post. And the manufacturer's own data sheet if the ware will hold food, which is the only place that question is properly answered.
Delivery and weight
Glaze is heavy, particularly wet glaze, and carriage on a small order can rival the value of the goods. Ordering glaze alongside clay usually spreads the delivery charge across a much larger order, which is one reason most potters place fewer, larger orders rather than buying as they run out.
Questions people ask about pottery glaze
Which glaze range should I start with?
Whichever your supplier stocks in the firing range your kiln and clay share. Consistency of supply matters more than the brand.
Is a dipping glaze different from a brush-on?
Yes. Brushing glazes carry a suspender so they stay put and build in coats. Dipping glazes are formulated for a single quick immersion.
Are UK glazes food safe?
That is a question about a specific glaze fired to a specific schedule, answered by the manufacturer's data sheet. This site never asserts it.