Which box dye for going from brown to funky grey/blonde TOMORROW? Pic attached

[MyHouseHasCrenellations]

I am/was growing out my grey (through decades of mid brown dyes) with a view to getting a hairdresser to give me a whole new look with ash blonde / grey colours running through, so that I didn't have to stress about covering my roots every two weeks. I was hoping for a classy but funky look as a darkish blondish...hmm it is clear I don't have a clue?

I haven't dyed it for two months but now I have an important job interview on Tuesday and it's too soon to get a strand test done (even though I seriously doubt that I need one) and get the hairdressers appointment in time.

I can't go with my hair like this, it's at least five colours, none of them gorgeous. So it will be box dye for me, I'm off to the big Boots/Superdrug.

Can anyone advise on the best route to go? I was going to try Colour B4 but maybe I should just lighten it then add grey tones?

Dont do it. Lightening hair at home is very different to using box dyes. Personally, I'd just leave the hair colour as it is for the interview but if you really don't want to then maybe use a semi permanent dye, or a wash in type thing to colour the greys.

Temporary brownish colour that washes out in 2 weeks?

The temporary ones tend to hang around on some hair. Good luck with the interview.

Could you use a root touch up spray or powder? You could buy one and try it out today. You could try a temporary dye but it might not work on grey.
Also get a trim and blow dry so that the style looks sharp, that way the colour won't matter so much, if the overall effect is pol ished.
Hope the interview goes well.

Belle Colour no. 7 or 8 works well on my hair (dark brown/grey) but result is always darker than shade shown on box.