Some interesting responses...
Hadn't considered the annoyance of being mistaken for Mrs DP if we were to split, especially if it were to happen on bad terms!
I think I'm just more for the traditional way of giving her her fathers surname. I can't see a reason she would need to have mine, she is as much of him and she is me and I imagine he (and his parents) would be quite hurt if she never got his surname, whereas I'm not really fussed.
As @Ladedada said I've had the privilege of carrying her and will hopefully have the privilege of breastfeeding and being her best friend and confidante as she grows up, as my mum is with me.
The only reason that would tempt me would be to carry the family name but I have 3 brothers who are already carrying on our family name with their children.
Re marriage it just isn't something I want, I grew up in a dysfunctional home, and see many dysfunction marriages. To me it's a piece of paper that makes it more difficult and painful to leave if/when you want/need. We got engaged as a show of commitment (also unnecessary IMO really), I think my partner hopes I will one day "come round" and get married but to me it's pointless. That's my opinion and stance on the matter, I respect yours so no need to be rude/dismissive or question mine. It isn't the point of the post.
I understand relationships end all the time, I suppose I just can't see myself feeling bitter towards her having his name of it were to happen, but that's one of those things you only know when you experience it.
Someone mentioned needing letters to holiday alone with DC - this was more of the kind of answers I was looking for. How true is this? I probably will holiday alone with her and my mother over the years, but surely anyone could forge a letter?!
Any other difficulties like this I could be faced with?