I'm guessing you are in the UK, being in the US myself I'd have no idea of online suppliers overseas.
As far as hatching, most folks make their own hatchery. You need an air pump, air line & airstone for aeration. A couple of empty 2 liter bottles, cut down so the inverted bottomless first one fits in the cut off bottom of the second one is the hatchery. A light source, which doubles as a heat source is also needed. These items go into an enclosed area that will keep the temperature at 80F, which is needed to hatch them in 24 hours.
I've found 2 tablespoons of uniodized salt, plus 1 teaspoon of baking soda will hatch up to a teaspoon of brine shrimp in a hatchery built like that. That is a lot of bbs, I'd guess that less than 1/4 teaspoon is more than enough to feed the average 200-300 fry angel spawn for 24 hours.
So, add the salt, baking soda, and eggs. Stir well, add the air line. add the light source, in an area that will keep it at 80F. Wait 24 hours
The next day, remove the air line, shine the light at the bottom of the hatchery. After about 5 minutes they will be hanging out by the light. I like to use a cup with a coffee filter rubber banded to the top to drain & rinse. Remove the bbs that is by the light with a turkey baster, squirt it in the filter. Let it drain, rinse with water, and feed to fry.
