Hi, congratulations on the birth of your dd. The first few months are extremely tough, but they do get easier as time goes by.
'However from after her early evening feed around 7 or 8 she does not want to settle to sleep at all and for the last few days has been staying awake for hours crying and crying ? last night she did not actually get to sleep until around 1.30am - obviously she is terribly overtired.'
I'm afraid it sounds more like she is obviously terribly hungry. It seems impossible I know but babies are programmed to cluster feed in the evenings and the best thing you can do is not fight it, but sit on the sofa with snacks, tv remote, phone, novel and feed feed feed feed, - OR lie in bed and do it. It is EXTREMELY important that you do do this as you are currently building your supply (assuming you are bfing) and your hormone levels are set in a way that makes this whole thing happen in the evening (unhelpfully I know).
Please listen to your baby and don't try to interpret whether they are tired or their needs. They managed to satisfy their basics biological needs in the womb.
There is time to get them into patterns and when they become a bit more involved and engage in the world around them then it can start to be argued that they might need help to 'fit' into it.
But for now, just feed whenever she looks like she's about to start getting grizzly.
hth