Have I got it right?

If the light brown dye is lighter than your natural hair, you probably won't need 3 rounds of colour remover (unless you have been dyeing it over and over for many years)
Then it all depends on the shade of blonde you want. 30 vol on light brown hair (possibly lighter after the colour remover) will get you straight to platinum very quickly, you could use a lower vol if you want a darker blonde or are concerned about the condition. I would use no more than 20 with a good powder bleach especially if you aren't experienced at bleaching. Lower vols give you more time to apply it all.
The most important step that you have forgotten about, is the strand test. Always strand test the bleach so you know exactly how long you will need to leave it on. Everyone's hair reacts differently, the amount of lift you get will depend on your hairs texture as well as the colour.

Thank u for ur advice.

I was hoping to be able to get it light enough to put a natural light ash blonde over the top. It was also that there's a coppery/ginger tone to it and I wanted to get rid of that.

Which bleach and toner would u recommend to a first timer please?

Thank u again x

You don't want to put a natural light ash blonde over the top unless it's an ash toner.  Blonde dye is essentially bleach, so you'd be double processing it.

A lot of people on here like Matrix Light Master bleach and make their own toners by mixing blue and purple dyes in a bowl full of conditioner (just a teeny, tiny bit of the dye, like just dip the tip of the brush in it).  That way you control the strength of the toner and can match it to your hair.