I just had a quick look on Smyths' website. They're anticipating stock in around the 17th to 24th July.
https://www.smythstoys.com/uk/en-gb/toys/fashion-and-dolls/my-little-pony/my-little-pony-potion-dress-up-assortment/p/189866 (https://www.smythstoys.com/uk/en-gb/toys/fashion-and-dolls/my-little-pony/my-little-pony-potion-dress-up-assortment/p/189866)
Argos has the magical kiss Celestia in stock. https://www.argos.co.uk/product/8560858 (https://www.argos.co.uk/product/8560858) Magical mane Rarity https://www.argos.co.uk/product/8218973 (https://www.argos.co.uk/product/8218973) and the dress up ponies https://www.argos.co.uk/product/7650721 (https://www.argos.co.uk/product/7650721)
There are still tons from the older ranges available though.
Nice find :D
Smyths does say in stock and out of stock at the same time mind you. And in my experience Smyths also tell you something isn't there when it is there...so...
Example of how reliable Smyths' website is for instock details in the spoiler below xDD
Spoiler
https://www.smythstoys.com/uk/en-gb/toys/fashion-and-dolls/my-little-pony/my-little-pony-retro-pony-packs-wave-2-assortment/p/176806
Check the store if in the UK and are allowed to go out (that won't be me till august at the earliest, but it says the same message for my store as well).