Disclosing an existing side business to employer - risk of disciplinary?

I'm a senior software engineer at a software consultancy in the UK for past 6 years in Northern Ireland. The consultancy works across a wide range of industries and software types.

In my own time and on my own equipment, I've built a web application that has been live and generating revenue for the past couple of months. In the last month, it has picked up some traction revenue wise, It's in a completely different domain to my day-to-day work.

My employment contract requires prior written permission from the Managing Director to engage in any other trade or business, with consent not to be unreasonably withheld. I haven't yet obtained this permission but I'm about to proactively request it from HR.

Could I face disciplinary action for having operated without permission, even though I'm now voluntarily disclosing it?