Question regarding predicted grades?

Ok I wanted to ask a question but not sure how to exactly put it so here I go with a bit of background on my situation:

So basically I've obtained by A-level results and they were nothing spectacular, my desired course to do at University is Mechanical Engineering but due to my grades my predicted will not be around the requirement for Mechanical Engineering. I've been suggested and I thought about it myself to do Engineering with an integrated foundation year and the requirement for that is BCC to CCC it varies according to the admissions tutor.

Now I believe my predicted grades will be around the integrated foundation year course requirement so I will have to apply for that. Since my exam results I've gathered a new passion and new ambition to work harder than ever and to prove my teachers wrong, this isn't me being delusional or giving myself a false sense of hope that I can achieve the best, it's my renewed confidence and passion to achieve the best and knowing I can if I work harder than before.

So now take this what if I've gotten the predicted grades for the integrated foundation year course and I've done my personal statement and sent it off to the universities and lets say I get the place for that foundation year course. Now after my A2 results what if I get e.g. ABB or AAB or something along the lines of that and with those results I do fit in to the requirement for the original Mechanical Engineering course and don't have to do the extra year. Now what if I get those results how can I get into my original desired course and not the foundation year course? I hear people talking about Clearing and Adjustment but please brief it to me according to my scenario.

Thank you.