Great high street SLS-free shampoo

I have an allergy to SLS on my scalp, so have to use hair products suitor it.

Many of the ones available are ridiculously expensive and don't seem to be particularly different to budget brands. Faith in Nature provide a good middle-ground of affordable products that do what they say on the tin (well, bottle...).
I use the coconut version as well but the lavender is my favourite - used alongside the FiN lavender conditioner it gives a heavenly- scented gentle clean and condition, though it can leave my hair a bit frizzy so use a hair serum to finish with for best results.