I would be with Marie and Starlight on this one Verity -
No one would EVER suggest to around here that "you couldnt do it" and Im not saying that you cant!! but, like Marie said, I think you would be better making a little bit of a more realistic goal - e.g. 3 stone (HUGE amount of weight to loose) and then anything after that being a big bonus.
Im just saying it because I know how disappointing it can be to set your goal and then not to achieve it (but lets face it, by any of us loosing any weight, we ARE achieving, just not hitting our set goal may make us feel like we're not) and I would hate for you to be down because of that -
I went wedding dress shopping on Sat and the lady (who was brilliant) gave me one brilliant piece of advise - she told me that although I want to loose weight etc, it would be fine but from her experience from dealing with brides, she would advise to loose what you loose, dont get too worked up about not achieving what you wanted to - she said if (and shes seen it happen) you get yourself all worked up about a particular weight you risk getting completely stressed out, your skin breaking out, hair loosing its lustre all because of it!!
I think you should stick to it and do your best and know that you will be a stunning bride!!!! with a beautiful "new" figure (and 2, 3 off stone will give you this!) glowing skin and a smile!!!!
The very best of luck pettal!! you'll do brilliantly