This is an intuitive feeling you get. It is usual when you are asked to make decisions but have no reasons for your decision. We often make these decisions in times of stress or under pressure.
I wasn’t sure which job to take but I went with my gut feeling and chose the job in London.
Remember that you won’t do yourself any favours if you simply throw these idioms into conversation during your IELTS interview. You must practice using them appropriately before the exam.