Wow, how weird... it's like I've just read a time-travelling post that I could've written 10 years ago.
I've had a look at some of your earlier posts and I can relate to a lot of what you've said. Like not fitting in with girls; being a 'tomboy'; feeling like everyone else had been given a user manual on how to be a girl or a woman & I must've missed mine; feeling betrayed at puberty; thinking if I could just figure out that one elusive thing I'm missing, I can finally be happy with being a woman. Apart from your attraction to women, I could probably have written every word you've said.
I'm not sure how old you are but I'm willing to share that I'm in my mid-40s. I'm also a mother of two teenage children, one of whom is on the autism spectrum. I'm also based in the UK.
Are you sure you're not me?

All I can tell you, after having struggled for decades to try to figure out whatever it was that every single woman around me seemed to 'get' that I didn't... is that it doesn't go away on its own. It gets worse as time goes on, until you pluck up the courage to do something about it. It sounds like you've reached that point now, and I can tell you from personal experience that transitioning is the only thing that has quietened my mind. I now pass 100% as male in my day-to-day life and I've never been happier in my own skin, nor more at peace with myself. It's cost me a great deal in terms of my family, but to be honest it's been worth it. If someone is willing to reject you because you need to be happy within your own skin, they don't really love you do they?
The way you describe your life so far suggests to me that you have had a consistent and persistent male gender identity from an early age, which is exactly what a GIC is looking for when they diagnose Gender Dysphoria. You've mentioned that you're going to your GP to get a referral to a GIC; that's an excellent first step, and one I highly recommend. I'm not sure which part of the UK you're from, but Scotland and Northern Ireland each have only one GIC; Wales has none; and England has 7 which have a wide range of waiting list times (Daventry & The Laurels in Exeter are the shortest; Charing Cross and Leeds are the longest).
Your changes on T will be slow & gradual, hopefully giving your daughter time to get used to them. I didn't start looking remotely male until I'd been on T for 8 months. It's just tiny incremental changes that creep forward so slowly that they're barely noticeable on a day-to-day basis; eventually they all add up to a huge change but it's months (or years) in the making.
You're fortunate that your partner is bisexual; in this case, there's a chance that she may want to continue with your marriage whilst you transition. I'd recommend sorting out what you want to do, and then have a chat to her to discuss your future. Personally, I waited until after my first GIC appointment before telling my husband. I needed their support and guidance because I knew it wasn't going to go well (he's homophobic). Only you can judge your own relationship, but I can tell you this: transition is a marathon, not a sprint... especially on the NHS.

You have a wait of at least several months before you can go to a GIC, so use that time to solidify your plans. Yes, get a part-time job if you can. But also look into alternative housing options (there are some housing associations and charities - including Stonewall - that can help with accommodation if things turn sour).
Also, if you suspect your partner might kick you out and take the kids from you when you come out, I strongly urge you to pre-empt that. End your relationship before coming out, and take the kids with you. It's hard to do, but it's the best way forward if you're at significant risk of losing your kids. But as I say, you have several months ahead of you before you can begin medical transition, so use it to your advantage in whatever way is necessary.
A very wise person once said to me: Don't live your life for other people, because you'll still be living it when they're gone.
I wish you well. Feel free to respond here or to PM me if you want to chat (you can do this once you've posted 15 times).