When you learn about roundabouts it can be one of the most challenging elements of learning to drive, at first glance they can be daunting and also quite scary. However, with some basic rules to follow, and using a well-planned out approach they can become much simpler. The key is to always apply the basic stay in lane principles unless there are road markings or signs that instruct you otherwise. Take a look through these images as they should help you with understanding when to signal and which lane to select.
One of the key things that you must always remember is that roundabouts come in many different shapes and sizes, so keep your speed slow on approach to give yourself more time to read the situation and prepare to stop, but planning to go if it is safe, 2nd gear is always sensible on the approach as it will have slowed you down sufficiently and at the same time, you should have enough acceleration to move off still if you have not completely stopped.
We hope this will help you learn about roundabouts, but if you are still finding it hard ask your instructor to spend a lesson focussing on these principles.