All the language centres in Qatar do preparatory courses for IELTS. You should really do a course no matter how good your English is as it will show you how to do the IELTS exam and give you practice. If you need more advice (free) contact the manager at Alexander Language Centre on 4436 4425. They run courses and also do individual tuition with tailor-made courses to help you in any areas you are particularly weak.
All the bookshops will be happy to sell you IELTS materials.