Small bottle of Johnson's baby shampoo (£1) will cover all your washing needs including you, clothes, and dishes. Lasts ages.
My total kit (and I might miss things off)
We have been weekend walking the Northern coast of the SW coast path this year. 20 miles per day is tuff schedule. There are sections where you will cover 8 to 10,000ft of accents and decents in 20miles.