Welcome to YT!!
Glad to have you both here. My 2 are also 7 - I adopted them when they were 2 yrs old.
I'm not sure which of the foods we have in the states that you would also have in England. We have a number of UK residents here on YT - hopefully they can point you in the right direction. I do believe feeding a high-grade food is important - such as Innova, Merrick's, Wellness -- there is a lot of info in the Health & Diet forum
Also, you may want to find a good oatmeal based shampoo & conditioning rinse to help ease the itchiness -- always remember rinsing the shampoo out really well is one of the most important steps of the bath. If you use a rinse out conditioner - then rinse well, as any residue on their hair and skin can cause more problems