Expanding/stepping away from business

I have been running my company now for 7 years and working in my industry sector now for 11 years.

The business is essentially just me picking up a phone and selling to other companies. I earn a good living doing what I do and I am proud of the business I have created but I am ready to step away from the telesales role and want to learn what I can do to take the company to the next level. Next level being I am in a reactive rather than proactive role.

I have never paid into marketing the business in any way and have always just relied on an old fashioned approach of picking up the phone and selling, retaining custom etc, however after 7 years I want to move forwards.

I haven’t got a clue where to go from here or where to start.

Essentially I need someone to pick up the front of house/sales tasks, service clients, generate new leads, cleanse and introduce new data. I think I need some kind of marketing strategy and someone to run a campaign too. Am I on the right track here?

Once a client has an enquiry I will pick up the client and provide quotes, artwork, invoicing etc (reactive)

Where do I start, what companies or individuals are out there and is this the right path to take? Is it worth spending the money to do this?