One of the unis at open day, in their welcome speech, told us that basically they make the conditional offers higher than the majority of students achieve. The reason is legally if the student achieves the grades they then have to give them a place, and if it was lower they would be way over subscribed. All unis do it.
On average at least half the students don't achieve the grades in the conditional offer and the uni then picks and chooses who to give a place to to hit their optimal student numbers.
My daughter was lucky in the fact many unis offer her course (law), so could look at high versus lower requirements,
However she had a situation where a lower grade Russell group offered her a non conditional offer and asked her to accept and reject all other unis, as such her a level results wouldn't have mattered, she was guaranteed a place, but she took the alternate decision and rejected the non conditional offer and went for the higher ranked uni, as she preferred it for a number of reasons, but the offer was conditional on her achieving three As at a level.
She did achieve it, but as you can imagine we had some angst from her in terms of whether it was the right decision then waiting for the results to come in. Rejecting a non conditional guaranteed place, in favour of a conditional on a level results place was a very difficult decision. Both were very good unis.
Ultimately she made the right decision, but genuinely if it had been me, I'd have taken the non conditional one.
I'd also ask her to look round the unis, they can tell if they like them, from the campus to the culture and that's really important.