Re bfing, I think it is a tricky thing for most women to establish especially if you aren't surrounded by experienced bfers and have no idea what a good latch looks like. If you add in complications like Seven's, it's can be very hard to maintain, specially as - and I was totally unprepared for this - the slightest hint that your baby isn't rolling off your boob having gorged themselves on the finest quality hind milk and just about everyone is waving a bottle in your face, midwives and health visitors included (I know! those people who sort of hint that you will go to prison if you don't breast feed are first in line to intervene with formula!). Also, IME people who love you and see you struggle try to help by suggesting a bottle or even saying you're making it hard for yourself if you don't. It is quite complicated.
I would say that for us it really worked out in the end (recent soreness notwithstanding), though it took me and DS fully 8 weeks to get it going properly and he went from the 75th centile to the 0.4th in that time, so the pressure to 'top him up' was huge. I didn't and his weight bounced back (very hard actually - he hit the 90th at 6 months) so retrospectively I'm very happy that we stuck it out. For me, it is worthwhile in the sense that it felt symbolic of the way that (often but not always well meaning) people - family, medical professionals, writers of baby books (fuck the baby whisperer, is all I have to say about them) strangers in the street, try to intervene in your relationship with your children and have you full of doubt about your understanding of your child. So sticking it out felt like a defence against that process, and forms a core of self-belief I have about me and DS, about our relationship and the way it is unshakeable. I should say that breastfeeding itself didn't cause this - but my feelings about it and my experience of it have become tied up in those beliefs I have about the relationship. I feel sure that if I had been in a position where bfing was untenable for us, as long as I made the decision about introducing formula rather than being pressured into it, then I would probably feel the same about feeding formula. I've met several mothers whose own decision to introduce formula was a core part of them empowering themselves as mothers, just as I see bfing in our circumstances as a core part of how I found my own power as a mother.
Anyway, sorry for the essay. Re property buying etc. - I moved from Yorkshire to London the week before I had DS. It was fine, but I have planned a more relaxed pre-birth period this time... Do you have to disclose you're pg Beaver on your mortgage application? If you are sure you are going back and your credit is good and you can handle it, I can recommend an unsecured personal loan as a mat-pay supplement. You have to take the amount that would allow you to make monthly reps on the mortgage plus the loan amount, and either have a pay-off-at-or-by-end-of-mat leave strategy or be able to cope with payments on your reinstated wage.