I have just seen elsewhere a petition against Royal Mail restricting the posting of acrylic paints. I have not heard it here so am surprised. I presume it is pukka so I have signed at link, it only needs another 300 and seems legit so have a think if it will disrupt your hobby.
[URL="https://www.change.org/en-GB/petitions/royal-mail-lift-the-restrictions-on-shipping-water-based-paints"]https://www.change.org/en-GB/petitions/royal-mail-lift-the-restrictions-on-shipping-water-based-paints[/URL]