I live in the UK. What is the ruling on buying and selling removable tattoos?

Tattoo as a term has two meanings. The first refers to permanent tattoos that involve injecting dyes into the dermal layer of the skin (containing blood capillaries) with a needle. The prohibition of this kind of tattoo in Islam is based on authentic traditions that declare any individual who performs them on others or gets them done to be cursed. Abdullah Ibn Umar narrated that the Prophet (peace and blessings be upon him) cursed both the one who gives tattoos and the one who gets a tattoo done.
The scholar Al-Hafiz Ibn Hajar wrote in his book Fath al-Bari that tattooing is prohibited because it accrues the curse of God. Moreover, the tattooed spot is considered impure because blood clots form under the puncture wounds that need to be removed even if this causes injury unless there is a fear of ruining or hurting an organ. Only then is it permissible to keep the tattoo and repentance is sufficient to lift the sin. This applies equally to both men and women.
As mentioned above, when the removal of tattoos necessitate causing injury or harm to the body it is impermissible to remove them. God says in the Quran, “And God wants to lighten for you [your difficulties]; and mankind was created weak,” and “God intends for you ease and does not intend for you hardship…. “ He also says, “He has chosen you and has not placed upon you in the religion any difficulty,” and “God does not charge a soul except [with that within] its capacity. It will have [the consequence of] what [good] it has gained.”
As for praying while having tattoos, it is permissible because the matter is classified under excusable impurity. Imam al-Nafrawi al-Maliki said, “If someone has a forbidden tattoo, he is not obliged to remove it with fire; it is an excusable impurity and prayers are valid while having it.” Fasting is permissible as well because it has nothing to do with having a tattoo.
The second meaning of the term refers to removable tattoos that fade in time or by water or any other substance. Removable tattoos involve drawing on the surface of the skin without puncturing it with needles or any other object. Removable tattoos, used for adornment and accepted in some cultures, are permissible because they do not it involve skin penetration and are easily removed.

The ruling
It is permissible to sell and buy removable tattoos.
And God Almighty knows best.