Herbatint can return your hair to its natural colour. If you want to darken your hair by 2 or 3 shades:
to obtain a Dark Blonde (6N) tone or lighter, mix a Natural (N) tone with a Gold (D) tone
to obtain a Light Brown (5N) tone or darker, mix a Natural (N) tone with a Copper (R) tone
Remember to reduce the processing time by 10 minutes, bleached hair is particularly porous and it absorbs more colour.
It is not recommended to colour your hair immediately after a perm. It is better if you wait around two weeks.
The processing time should be reduced by 10 minutes and you should choose a lighter shade than the one you would like to obtain.
Henna creates a sheath that wraps the hair, thus hindering colour penetration. Whatever colouring you would do, you will obtain limited results and an uneven colour. Before colouring again you should wait for the hair to grow back.