I had the brown teeth pronlem you mention Ellie Anne, my, then 5 year old DGS asked me why my teeth were so brown. My dentist suggested I had 'composite' put on my teeth and that has worked very well.
I have tried to find out exactly what I had done online but all I can find is information about composite veneers, which are very expensive and I certainly didn't have that treatment.
The dentist just spread or painted a substance on my teeth that hid the brownness where the natural dentine had worn away, a bit like nail polish, I think!. It was done about 5 years ago and has worked very well. I cannot remember how much it was, but more likely £100 or so for 4-5 teeth, not the £500 plus quoted for each veneer.
If you have a private dentist I would ask them about it. Possible get the exact name for the treatment I had and google it.