Thanks for your kind thoughts ladies - I decided there was no point in doing a meltdown, so am a bit more chilled about it all today.
Found out today that someone who works on my floor lives in St Leonards, she's back in the office tomorrow so am going to ask her how she gets on with the commute - because yesssss St L is back on the home finding agenda, commute or not. I had a good long chat yesterday with the biggest London housing association about shared ownership and the stark reality is that I wouldn't be allowed anything bigger than a one bed flat, none of which come with gardens.
So shared ownership is out. Buying on the open market is also out. Which leaves buying outside London the only option left to me.
I was chatting with a friend about it last night, and she pointed out the obvious - that even though I love my job in London, why don't I look for work in East Sussex, then the commute wouldn't be an issue...which is a very good point. Then in a weird coincidence, I had two job agencies call me today, so I mentioned it to them and they are both going to canvas employers down there and see what they come up with.
So, I am going to try the commute out in December and see what it's like.