No, but it’s an option, with a significant price-tag.
Employing an ad agency means that you are using professionals to deal with all the complexity and workload. This means you have more time to work on your business and some peace of mind that a good job is being done.
Obviously, this comes at a cost, and so, in addition to your advertising budget, you will need another budget to pay for the advertising agency. It’s probably rare to find an agency that will work for less than £1000 month.