Loughborough is a great university (biased!) as I understand in Swansea.
When I looked into it I think the entry requirement was set my the IMechE for acredited engineering courses, so I am not sure where that leaves you, or how it effects clearing.
Certainly looking into it early will do no harm, and I would would for instance ring Loughborough's admissions team and ask the question directly. They are nice people and will appreciate your honesty and contacting them.
Obviously also try and get the A, as you might well surprise yourself as I know a lot do!
Certainly, 6 years on, I am really enjoying having done Mechanical engineering, so go for it. Any questions shoot me a message if you want.
Daniel