Possum skull I have (ANY bone/vulture culture enthusiast, PLEASE click, bc I have a question)

 

(I know I need to clean it btw)

My friend saw one of the groundsmen at our school unblocking a rainwater pipe and saw him put this skull in a bush, and she knew I liked bones, so collected it for me. (She's so nice :3)

I was thinking of using it for my art assignment, since we have to make a doll that's either future-proofed, a helper of the environment, or an animal protecter (or a mix of those).

This is the design: (not really important to this blog, but you can look at it anyways)

 
(I have other designs I could use, but my art teacher really likes this one, so I'm gonna do it because if she likes it, it may be better marks) (plus it was my original design and I like it the most)

I've had the skull for ages now, and it's just been sitting outside (not in the sun unfortunately, so no UV cleaning or whatever the special word is). 

If I do use it (which I probably will) I would need it clean rather soon and was wondering if anybody here knows a fast-ish way of cleaning bones. I don't exactly need it to be white, but I do need it sterile/clean. My art teacher said to put it in bleach, but anybody that's done the research knows bleach is bad for bones. 

I'm pretty sure I'll be able to clean it, but I know that somewhere along the way, there's going to be Hydrogen Peroxide involved (maybe it's just for the whitening and I've just accidently linked it to cleaning, hopefully so). If there is Hydrogen Peroxide involved in the cleaning, I'm in trouble, since I have no way of getting it.
Why?
Because I'll have to ask my mother for her to either buy it, or to let me go to the shops (which I never do so it'll be suspicious). I know that it's also in some hair products, but I can't just randomly ask for some large amount of a certain hair product without my mother asking why (again, I never ask for hair things, so it'll be sus). If there is some sort of easy to get/most-homes-have-it substitute to hydrogen peroxide, I'll be really happy. 

(The reason that I don't want my mother to know is because she had found the skull ages ago, like when I had first gotten it, and had told me she doesn't want me collecting bones because of diseases and she wanted me to throw it away, and since I obviously haven't, I don't want her getting angry at me).

I was thinking of soaking it for a bit, then simmering it and/or steaming it.

Please please pleaseee tell me if there's an easier way or something, I kinda really need help. What I have been looking at is three blog posts/idk what there's call, info things, about bone cleaning, linked below.

How to Clean Tissue Off of Bones before Whitening - Mom Goes Camping
How to Sterilize Animals Bones for Display and Collecting - Mom Goes Camping
How to Whiten Animal Bones for Display (Step by Step with Pictures) - Mom Goes Camping
(I know it's the same website, but it's good at explaining, if there's a better one, please tell me)