If I am under the minimum age for a tattoo in my country, is it legal for me to get one somewhere else?

Hi Jaime, of course, it is legal for you to get a tattoo in a country where your age/the law allows you to get tattooed. It is not that you are not allowed to get a tattoo at your age, but rather the tattoo artist is not allowed to tattoo you, because you cannot legally sign the consent form.
In some countries, you can get a tattoo if you are under the minimum age with the consent of your parents, who are legally allowed to sign the paper for you and allow the procedure. Although this is not the case in the UK. 

Barber DTS