Agree that it's a good idea to check before applying. However just to note that an unacceptable ref wouldn't usually be grounds to reject you. If it was necessary to consider your app, they'd just contact you for another one. The only issue there is if they set you a relatively short deadline to provide it.
It may worth explaining that you can provide an academic ref by DATE X. They may ask you to submit the application without one for now, (but you shouldn't do that unless they agree it's okay).
Professional refs are usually okay for mature students, but if you are completing a course now, they'll almost certainly want an academic one.