Some butchers may sell them already stuffed, and / or rolled up with a layer of caul fat around them.
The joint will weigh in the range of 400 g to 1 kg (14 oz to 2 pounds).
They can be cooked whole, or cut into lamb noisettes, and then cooked as such.
They are easy to carve.
For roasting. Allow 1 per 2 people.