Been looking into getting a pet turtle and looking for advice

I have been interested in reptiles my entire life and more specifically over this year turtles. I have doing a lot of research into them both to do with care and just learning about different species in general. I would like to be able to own on as a pet and have been looking into it a little but do not want to make sure I do things correctly. I am from the UK. I would like to get some advice on thinks I should consider and the best way to go about obtaining one that will be in good health and obtained ethically. I do not have a preference on species but would think it would be reasonable to go with one that is easier to care for a as a beginner. Are there any breeders/pet shops in the UK that are reputable that you would recommend that maybe is where the you got yours from? Do you have any recommendations and things to consider in regards the the care and housing of the turtle?

I just want to make sure I do it right