Dark blonde -Colour b4

You could safely do either one of those. Some box dyes contain a little peroxide when the colour is a shade of blonde so it may lighten your hair while it colours (check the box for details and ingredients for this) or it may just colour your hair a slightly darker shade than the box colour if it doesn't have any peroxide.

As you used Colour B4 and not a bleach it won't harm your hair if you do decide to use a bleach bath first. As you only want to go slightly lighter it's a good way to lighten up just a couple of shades.

You obviously don't need a straight up bleach if you're planning on just lightening your hair a little bit, so either way you'll be just fine.

Thanks, i did a bleach bath and then used a light ash blonde. Its lighter but more gingery, i don't fancy bleaching it again so think i'll use a medium ash blonde and toner to get the ginge out 🙂

Sounds like a plan to me! Good luck.

when u bleach, start with the midlengths and ends, leave them to bleach as light as u want them, then put your bleach on the roots for the last 5-10 mins =]