You can do IELTS for £135, 4-5 weeks of review at home or enrol at your local college then take the test when your confident enough to take it. Result of the test will be 13-14 days.

As far as I know it is up to you also with the assessment of your instructor if you are already ready to take the ESOL exam if you chose to go with it so I dont think 5 years for you is necessary unless you are a beginner which obviously your not.

Like I said give your college a ring as they can provide more infos for you, by the time they start speaking to you they will know right away what level you are on English Language.