The article
U.S. Marines change the women's uniform to allow enlisted females to cover tattoos | Daily Mail Online, indicates that the USMC are prepared to change their uniform rules in order to comply with their requirement that there should be no visible tattoos so, if the Royal Air Force were to adopt a similar approach, it would appear that Laura Hill might have to adopt another style of headgear in order to comply.
Removal of a tattoo is of course another option, and one which the Royal Navy certainly applied when a disenchanted young sailor had "I hate the Navy" tattooed.....on his forehead.
The removal was very painfully undertaken on unpaid leave but, when the sailor subsequently served in sunny climes, the words reappeared, albeit faintly, greatly to his subsequent regret, a feeling I suspect so many others must share.
Jack