Amalgamate client info for marketing purposes

Amalgamate client info for marketing purposes, I’m a sole trader and I’m trying to compile client information for marketing. (Name, address, email, telephone number, DOB) I’ve a little access database created as well as having a CSV file from my online booking system. A few hundred clients - not thousands. Ultimately, I would like the information amalgamated but don’t have the IT skills to do this myself.
Also willing to discuss advances with marketing too.
Thankyou