I had my BCG at 14 and have no scar (again I'm also very pale)- I'm doing Medicine at the moment, so had to do the whole health check forms etc, but they were happy that as long as I had proof I'd had the vaccine I was ok. I did have to produce a letter from the occy health I'd had it at, as I hadn't a scar, but it wasn't a big deal.
That said a girl on my course was in the same situation, went back and had a Mantoux test and it said she wasn't immune, so she had to be revaccinated, and she's ended up with a massive scar. I think i'll stick with the idea I had the vaccine therefore I'm immune.
There are also people who have never had the test or the vaccine according to them, so I don't know how big a deal they're likely to make of it. Depends on exactly what you're going to be doing OP and the uni's policy.