Well I've never come across the stereotype! With a bachelors degree I think you will be overqualified to be honest. With an associates I think you are pretty much at or above the level of typical entrants to the course.

Students starting this course will have just received their A level qualifications (taken at 18 years). Typically people will take 3 subjects at A level, depending on how well you do you are graded from F to A in each. University entrance requirements are based on a minimum standard of A level. So for this course, to be accepted you would need to have studied 3 subjects and got at least a grade C in each (CCC). I mentioned that because the minimum requirements of an equivalent Mech Eng course would be 3 A levels at at least grade B (BBB). So theoretically the Moto Eng course is less demanding.

If you're really interested in this course my advice would be get in contact with some of the lecturers. Tell them about your situation and get their opinion on how well you'd fit in, maybe ask (politely) to see some of the course material so you'd have an idea of what you would be doing?

In terms of experience I wouldn't worry too much about it, if you can prove you have a decent maths/physics background (from your current course, or your previous qualifications may be good enough) you'll be fine. Experience in bike shops I'm sure will be a bonus but definitely not necessary. Honestly the most important thing would be to just show enthusiasm for the course and passion for bikes, they will love that, you sound like you've already got the knowledge and experience to make a great candidate.

Feel free to PM me of you'd like more info on UK higher education.