Hi Kaz,
I also have 5 stone to lose. Am starting my diet soon and will be doing slimming world. I've spent a few weeks getting to know this site now and reading everyone's stories and I'm definitely ready to start losing weight. My head has been all over the place lately for lots of reasons and have found it difficult to start any kind of diet, but I've just been posting how I feel on here and it's really helped to a point where I'm ready to take the plunge now!
I've done Slimming World before also, but am going back to it because I find it so much more flexible than counting points. I think the key to sticking with it is to keep posting on here because the days when you need motivation or help will be the days when you will see just how much support you have on here. Also from what I've seen, those who have been losing and lost a lot have had such great responses from others, so that in itself is a great way to stay focused.
I would suggest thinking about what diet you think is suitable for you and when you decide, have a read through the posts on these boards for ideas and inspiration and you'll soon find yourself in the right mindframe to get on you weighloss journey.
Also, if you ever need someone to talk to, come and find me!
Bells