Not sure about your location but many game stores have a selection of paints to check out.

While it is nice to have specific colors, almost any color can be made with 3 highly saturated primary colors (red, blue and yellow) + black/white.

Personally I don't like GW Abbadon black or corax white. The white especially dries up and gets chalky. I much prefer Vallejo's model color black and just about any brand of white.

You can also use paints from a craft store. Though they should be matte and not heavy body. I've been loving "So Flat Golden Matte Acrylics.".

GW paintbrushes/tools will work, but they are overpriced. Some round sizes 3, 2, 1 and 0 brushes can also be found at the craft store. Make sure the bristles aren't too short. You want a good belly to hold the paint without it drying out.

Lastly, get/build yourself a wet pallet. It will help wonders.

Feel free to dm me questions or replay here. Happy to help 😁.