Welcome to this site @Quote_Queen_67 . You'll find a lot of support here.
I know most people have given you great info and resources but I'll chuck my 2 cents in. In my experience, the scans you're having will give your surgeon needed information but the exactness (I know - not a word) of the cancer won't be known until the path report after surgery. They will, however, dictate the immediate steps.
Cancer's not a joyful thing to have but it's really important to take one day at a time and try not let your mind wander too much into the what-ifs. And try to stay away from Dr Google. That said, there are a few sites that will give you real information. Moose and Doc (or something like that) has some good explanatory stuff as does the UK BC site. You can see my year of treatment by clicking on my name.
Re: telling kids. I had no choice but to tell them straight away as I had to pick them up en route from Breastscreen to the GP. They were 11, 12 & 15 at the time. I have kept them informed of everything at every stage and told them that I will always do that. I don't go into the what-ifs though - just the facts and then let them ask the questions. They know that they never met my sister because she died young from this disease. Keeping secrets can be so much scarier than the facts. They have been a massive support for me in this. My first surgery was on 21st December 2017 and one of my favourite memories is of the 3 of them lined up, peeling spuds for the Christmas dinner they prepared in it's entirety. Who'd of thunk it possible?
There's many ways of telling other people but do it at your own pace. For me, my husband told his family (I don't have any family who needed telling at that time) and I rang two key friends and asked them to contact other friends and be the conduit of information - I was having enough trouble getting through things without people constantly ringing me to see how I was. This worked beautifully. While I was in hospital, my husband set me up with a blog page so that I could keep people updated that way which was also a really easy way to do things. I kept the settings private and sent the address to those who were interested. I have found that it became a fantastic journal to sort my thoughts out and has become a record of the almost year of treatment.
I stopped work from diagnosis in early December 2017 until after radiation in October 2018. As the sole income earner for the family (and a paltry income at that), this was a major blow. I was, eventually, able to access Income Protection from my Super fund. Mine provides 3/4 income (after tax) but does come with conditions. I never had any trouble being approved for it, just a heap of trouble getting them to do the processing of the claim to get the money. My suggestion is to check your fund to see if you have this cover, or trauma cover, and once you've made your decision about work, to get on to it IMMEDIATELY.
Back to the kids... tell your kids' teachers, or someone in their school, as soon as you can so that they are aware of what is going on. I emailed my youngest's teacher at primary school. I was fortunate that I work in my two older kids' school so they knew what was going on, but as one was just starting there, we had some anxious moments as she was dealing with so much. I did access the Well-Being team at the school and they were able to keep an eye on the kids for any difficulties they were having. It may be worthwhile if you are having financial difficulties as well because many schools have a welfare fund for these situations to cover uniforms, fees, etc.
Take care.