Agree with OwThatHurt - your DCs age will depend a lot, if they are still at primary school, I wouldn't be basing any plans on the current system.
My DC1 is just starting school in September. When I was his age, universities were free to all and a 'full grant' covered hall fees and was enough to live off as well. By the time my DB (3 years older) went to uni, your degree was still free, grants still exisited but a full grant didn't even cover hall fees. By the time I went, grants didn't exist at all, everyone could get a non-means tested loan and fees were £1k a year and "would only go up with inflation". Then it was means tested loans and fees going to £3k a year, then we got our current system.
Basically, the rate of change over the last 20 years in higher education funding has been massive, and each change has made it harder for DCs from larger families with middle incomes.
If you can save anything towards uni age, I would do, and if when they get to 18 there's been a massive change again and uni is completely afforable then youcan spend it on a round the world cruise a deposit for a flat or somehting else worthy...