In this area of England you have to take the IELTS exam through
Mayflower College. You can sit the exam in Exeter and in Plymouth.
The first thing to do is to make sure you understand the test and whether you need to take it or not. This official handbook can help you with this.
The next thing to do is to decide when you want to take the test. You can use this internet page to find out exam dates in Exeter and all the information you need to apply and pay for a test.