I went to university in my mid-thirties with the same fears as you.
But it turned out that the student age-range was very diverse and, anyway, who I got on with socially was not determined by age alone.
Having said that, it pays not to be nor to appear to be a 'pompous old git' - which I am sure you're not.
As for being 'on a totally different wavelength', there are people of your own age 'on a totally different wavelength'.
Good luck with it.