Hi Gills, I have just lost 10st, it has taken me 3 years but and I stress but, I tried to do it alone for the first 2 and a half years, I have been on all the diets you can think of and for me the one I am on now is the best (you may find that another one will be better for you), I still have another 10st to lose, unfortunately I let my weight get way out of control and ended up at 31st 7lbs, I am now 21st 7lbs, I joined S/W at the beginning of November and have lost close to 4st since, I have good weeks and bad weeks, but on average I lose about 2lb a week, that's an incredible 7 and a half stone in a year...I eat so much food and I follow the plan as much as I can, I am human and I have days where I slip up, but S/W gives you the freedom, especially on the Extra Easy plan (there are red and green plans too, which are aimed at meat eaters-red plan and vegetarians- green plan)and it allows you to have lots of everything as long as 1/3 of every meal is made up of super free food...which is veg, fruit, certain meats, beans, fish, pulses and so on. Yes 10st is achievable within 1 year but as a long time dieter and one who has major amounts of success only to put it all back on and some, I would say losing at a slower 1-2lbs a week would be a better way of doing it, as you are more likely to keep it off in the long run (I lost 9st in 8 months to go on holiday and put it all back and a lot more).
Anyway hun, whatever plan you choose, I wish you the very best, gl with your journey.
Lily x