I have coached several cyclists in your category and they seem to do well as long as they can stick to the program. So it's important to find out ahead of time what kind of time commitment the plan will require. There isn't much point in hiring a coach to write up a plan for you if you can't stick to it reasonably well and that might be an issue given your other commitments. I'd ask the coach about expectations in terms of total hours riding per week, how many workouts per week and the length of the longest workout on the weekend.

Based on what you've said about your riding, you have plenty of endurance but you'd like more speed and quick acceleration to be able to hang with a group better. These are two areas where some very targeted workouts once or twice per week can help a lot. So I'd encourage you to consider it if cost and time allow. Wenzel Coaching certainly has a good reputation around here.