I have had a cough for about six weeks should I service my gprs?

Yes see your doctor. A chronic cough that goes on for weeks usually has a cause. In most cases, it turns out to be post-nasal drip from allergies or sinusitis, reactive airways like asthma or copd, or gastro-esophageal reflux. In some instances, it can be something more serious. Long-lasting cough requires a thorough evaluation & possibly coordination between many specialists, so get checked out.