I hope I am not sounding old-fashioned here, but you are dealing with the British embassy and their representatives.
If my wife and I had tattoos (we don't) I wouldn't take photos of these for the ECO.
Seems inappropriate to me.
Gosh, I must be getting old.
It is the thought of hundreds of thousands of grannies going around in "x" amount of years from now showing tattoos that freaks me out, but I won't be here to hide in the corner