If I were you, I would determine what exactly I want to improve to achieve actual Goal. There’s pointplay and matchplay, which (unless you have 6-day per week tennis regiment) is best improved by … playing points, matches, and simulated situations. While being aware of things like your typical issues. Nothing beats mindful experience in short/mid-term improvement.
You may also want to analyze your game for glaring gaps and issues. Technical, tactical, physical. You may want to address them first in like 3-6 month period before going deep into matchplay again.
You may also be after significant improvement, which may require all-around work: where you are good you can get better, get to next level; where you lack you can improve. Technique, fitness, focus, match-toughness and smarts, choices, understanding opponents’ games… here you can accommodate 10+ hours per week on court + extra fitness hours + good recovery regiment + reading some books and looking some tennis for the level you aspire for (not pro), and learning how they loose, how they win there.
But whatever you wish to afford, an on-court coach is an x5 multiplier, if not key requirement. Not because he mandatorily knows better than anyone on the internet, but because he can see you immediately from the side and give instant feedback. It’s totally invaluable!