Momo95, I'm not sure why you think you wouldn't be eligible to apply? BA are asking for the equivalent of A levels at BBC or Scottish highers at BBBB. Your 297 UCAS points is above the BBC equivalent, which would be 280 points. If you can provide a NARIC statement to that effect then it should at least allow you to apply. (ie. The type of exams you sit are not a hurdle, it's only the grades or their equivalent, which aren't worked out by BA but by the relevant qualifications authorities, who then work out how different exams systems compare. Basically, either you have the BBC A level equivalent or you don't...if you don't, then you need a 2:2 or a postgrad. Pretty straightforward!)
You can work out UCAS equivalents here:
Tariff Tables | UCAS | UCAS Tariff Table & UCAS Tariff Points
...and get the NARIC stuff here:
NARIC - Statement of Comparability
Obviously any further qualifications are only ever going to be a good thing, but if you'd only just started a degree course you wouldn't be able to put it in your application anyway, as you wouldn't have completed the degree. You could, of course, still talk about it during any subsequent interviews (should you so desire). There will undoubtedly be plenty of applicants who wouldn't be able to walk into an aeronautical engineering degree.
In my current career I've worked with a fair few individuals who required an access or foundation year after not initially having the grades for their desired course; to my mind, it just showed that they were prepared to go the extra mile and spend the extra year to get their qualifications. Whether they'd done access courses or foundations years prior to starting year 1 of their course, it didn't have any bearing on how well they ultimately did in their degree or, for that matter, in their job.
Are you sure you're not being held back in your applications by those B grades, rather than the Irish qualifications? Don't know where you've been applying but every one of the bigger departments seems to want A grades with maths and physics, wherever your did your schooling. Is there anywhere advertising an aerospace/aeronautical engineering course with B/B Maths/Physics as an entry requirement?
That's a bummer about the fee situation.
As far as lowering the bar, probably worth a look at Bealzebub's post (#1076) on the previous page.