Vauxhall Astra my car is making is blowing from the exhaust system,slight noise

If you run the engine then get a friend to hold a rag over the end of the pipe briefly then you should see the leak

Run your car into any fast fit exhaust centre and they will give your car a free checkover on the ramp and a report on what's needed .You are not obligated to get work carried out and can shop about for prices once you know what is needed .