Earning royalties whilst on benefits

HI, I am really hoping someone can help as my energy is very limited and I'm in need of some advice.

Basically I am long term sick with severe fatigue issues. Over the years, and with much help, I have put together a book which I would like to self-publish. But I need to make sure I am aware of all the benefit restrictions and rules surrounding this. I am aware of the permitted work rules, but I wonder if gaining royalties is the same as actively doing work right now? 

Because, my concern is that 'if" (and I know its a big if) my book sales went over the permitted work allowance one week, would my benefits be stopped? I cannot risk losing them.

And with the fact that it is a hobby and working hours are so minuscule - maybe 30 mins a month - is there a way round this, as in could it be classed under savings instead - which would allow greater sales revenue?

I basically don't want to let being on benefits stop me publishing. I know my book is meant to be out there, but I need some specific advise how to go about it all and I would really appreciate any help from an official advisor? Or direction to one online.

I am on PIP and income related ESA. The writing is done in bed on my laptop or phone or paper. My family help me  a lot of the time, and someone else is doing the admin required to get it published - as my condition limits the energy I have to do so. So I am not working and hope this wouldn't cause any benefit concern in terms of activity. But I would hopefully earn some royalty money and I wonder if there has been a precedent set by another author, or an artist perhaps in this same position?

As I say, any help would be greatly appreciated. I am grateful for a charity which supports disabled people to move forward if whatever way they can - so Thank you.

Charlie