Hi Lucy, welcome to social slimmers
There is no reason you shouldn't be able to lose whatever weight you want to as long as you follow the plan.
The only thing I will say is that SW usually only register people who want to lose at least 7lb.
SW is a very easy plan to follow, plenty of fruit and veg, meat, pasta, rice, potatoes, to choose from to keep you filled up, and a daily allowance for fibre and dairy.
Plus 5-15 syns to use each day on whatever you like