My ankles are quite weak and I am wobbly in my pointe shoes and I feel quite unsafe.
How can I strengthen my ankles for when I do my pointe class?

If you have a resistance band (like this http://www.physioadvisor.com.au/assets/256/images/13508256(300x300).jpg) then you can strengthen your ankles by putting your foot through the loop while holding the other end toward you and pointing your foot downward. But if you don't then you can just practice being on releve for as long as possible or put weights on your ankles and lift then up and down in a slow and controlled movement.