Bleach & Dye Dilemma !

Hey guys! This is going to come out a bit long,

I have natural black hair (I dyed it black once after I had previously dyed to a lighter colour, but has now faded to a dark brown and has been growing out for several months) and I'm looking to go an ash brown color. Now keep in mind I'm a total beginner at this...

Since I can't afford to shell out almost $150 for the salons here, I opted to buy my own bleach and dye. The clerk recommended to me a 40 volume solution (I forget if it was ammonium or peroxide) to mix with the powdered bleach, and then to mix the dye with a 30 volume solution. Originally, the clerk advised to bleach twice with 30v and then dye, but the dye color isn't 100% the colour I'm looking for either. The colour on the box said 'light ash blonde', and I was looking for ash brown, although the sample colour strands didn't look all that blonde to me -- the color is Rusk 8.01A if you want to google image it... but you really don't know how much you can trust those swatches, so I decided to bleach only once so she gave me 40v instead.

So I came home and decided to google some of this stuff, and came across many people warning against 40v bleach and that it should be treated like toxic waste, which has me in a panic mode -- plus I have to dye again with 30v! Is this safe for my hair? Or should I change it up a bit (perhaps go back and purchase the 30v bleach instead...?)

Thanks a bunch