A complete kit for bootie, hat and mitten is available directly from Blacker Yarn’s website.
https://www.blackeryarns.co.uk/

YouTube knitalong playlist to accompany the pattern can be found here:

If you want to knit this pattern seamlessly, there is also video playlist to show you how you can adapt the pattern for seamless knitting.

Please check the yarn requirement below. Estimates are based on the actual 6-9m sample, with a 10% buffer added. If you want to make all 3 items, add the length of the yarn rather than the number of balls.

Sizes
Newborn (0-3m, 3-6m, 6-9m)

Bootie
1 (1, 1, 1) ball, 33 (40, 44, 57) m/ 36 (44, 48, 63) yds.

Hat
1 (1, 1, 1) ball, 51 (62, 75, 92) m/56 (68, 82, 101) yds.

Mittens
1 (1, 1, 1) ball, 40 (46, 57, 66) m / 44 (50, 62, 72) yds.

Needles
4 mm (US 6) straight needles.
The video tutorial uses addiPremium Classic circular knitting needle 80 cm circular needles.

Other accessories
2 stitch markers (6 stitch markers are used for the hat)
Yarn needle for finishing.

Tension
20 sts × 28 rows = 10 cm (4 in) in st st after blocking.