Did you go through the exercises on the "weight goal" tab. Usually your ideal weight is based on height and bone structure. I first started down this road when I realized I weighed double what I should, shocking to say the very least. Just take it one step at a time, figure out what your bad habits are and then slowly chip away at them one at a time and replace them with good habits. I really can't give you a good goal weight to lose in a year, but I will second that 1-2lbs/week is reasonable and healthy, which is 50-100lbs in a year. 10 stone is more than that, so you might want to shoot for 5-6 stone-ish if picking a number is a pivotal exercise for you. The number on the scale is important, but it's much more important to focus on being healthy and making changes that you can live with for the rest of your life.
Two other bits of advice I'm going to offer are to drink water water water, it really helps, baseline 64oz + 8oz for every 10lbs you want to lose. If that's too much water to drink in a day, just aim for the first 10lbs and throw down 72oz. Another thing that is crazy important to me is self forgiveness. Somehow or another cheating on the diet and completely throwing in the towel in a vortex of self pity are very intertwined events for me. And even though I have learned that I can climb back on the wagon after a fall, it doesn't come naturally to me, it requires focus and effort - which is nearly impossible if I'm swimming in guilt. So I take a deep yoga breath, pull up my big girl panties, exhale and move on. I refuse to be defined for all eternity by a handful of diet sin.
Starting weight: 244.6 lbs. 10/01/09
Pounds lost: 80.6 lbs
Current weight: 164 lbs
Goal weight: 120 lbs
Weight to go: 44 lbs
Goal Date: 1/1/13