Seek out some support for yourself where you can be completely honest about how you feel: you will hold back your fears, around your child (of course), but possibly around relatives too. If you want to question, and deal with what-ifs (if you are that kind of person, some of us are, some aren't) then you don't need to be told not to think about that, or to stay positive. It can help to have somebody who will listen to your fears. Voicing them will not make them come true. But it might help your head. We were given a CLIC Sargent social worker, who has been wonderful support for us. But, a counsellor could also be helpful. See your doctor. Or, find a spiritual ear. All hospitals have non-denominational chaplains to talk to.
In fact, see your doctor anyway. You will need that kind of support. As time passes, you may need sick notes, or help with forms, let alone any medication that you might need. I'm not saying that this is a given, but please remember pills (sleeping/mood) are there if you do need them.
For the stay in hospital you need plenty of water to drink and hand cream. I dried out so much from alcohol hand gel that my hands got covered in a big rash which cracked and bled. Not much fun. Also, try and get out for some air at least once a day. It is scary to leave - especially if you are waiting for doctors/treatment/tests/test results - but the nurses are there, and possibly other staff - like social workers, play workers, etc - so try and get yourself a break.
Keep a notebook. You will get told different things by different people. For me, it was the most difficult and frustrating part of being in hospital. I was sharing care with her dad, and each time I'd come back in, something different had been said. For example, a consultant would say, she needs a transfusion, then Sister would come along and say they couldn't do it that night, so they'd wait, then she would order blood tests and say she didn't think she needed one (even though counts were same and consultant wanted it doing), then consultant would be back two days later wanting to know why it hadn't been done... Believe me when I say, I fought and argued, but you get sick of being looked at like the difficult parent. And I could have taken it further, it is easy to think back over the things that happened and say, I should have complained (the example I gave is mild), but you feel beholden to these people, you essentially have to live there, and the next thing always comes along before you get a chance. I should have written everything down, so I could clearly argue my case should I have chosen to. It would have given me more control in a situation where I felt powerless; it would have given me a record for when I wasn't there (if dad had done it too), and it would have been helpful to have my own notes to look back on as treatment progressed.
If you do need somebody to speak up for you in hospital, contact PALS. Every hospital should have this patient liason service. They are there to act as a mediator if you feel staff aren't listening to you.
Get ear plugs. I wish I had. Hospital bays are very noisy places at night.
Take some creature comforts for you: your own towel, perhaps your own pillow and blanket. We bought a mattress topper from Argos to cover the fold-out bed. It made it a little better.
You should be entitled to DLA. Get a form, get somebody to help you fill it in. This will enable you to apply for a blue disk later if you need to. It is extra money, it is disability benefit. Forget how you feel about claiming benefit, if you are against it, as you will need it. Hospital stays get expensive. You will miss work, and if, like mine, your child has leukaemia, treatment lasts for a long, long time. People's sympathy does run out, and days off become unpaid quite rapidly. Apply for everything you can get.
Charities can also give you some financial support. They raise money to help people like us: it is the reason they are there. If you need some more help, ask them.
CLIC Sargent also have volunteers. When you get home, if you need someone to stay with your child so you can go to an appointment/the shops/just have a rest, then they have CRB checked volunteers who can do that for you.
Obviously, you will tell your employer, but tell your union too. If you aren't in one, and can be, join one. You might need their help in the coming months.
If your child has leukaemia, which is a critical illness that lasts for longer than 12 months, you are covered under the disability act as their carer. This is important to know for entitlement at work. You are entitled to 18 weeks off, unpaid, and this can be taken as daily increments, although you are supposed to give 21 days' notice. But, you are also allowed to take 'emergency' dependent's leave. A reasonable amount. What that means is unclear, but you do have some rights and protection from the law. I hope your employer is compassionate and stays compassionate, but in case they don't, you do have some support. If you don't have union, try charities or your social worker. And remember you might have legal advice through your home insurance.
This sounds quite serious in places, but these are all things that I have worried about or encountered over the past 18 months. If I think of more, I will update.