When I lived in Leeds I used to attend the Open Coffee meetings (monthly) and the BarCamps (annually), where people would talk about start-ups and start-up events, so you could target these meetings (if they are still going). I doubt you could target students directly without appearing to be spammers.

You (perhaps collectively with other roundabouters) could try holding some sort of competition for students. I am sure academics at universities would help to promote something like that to their students and you would be able to see which students are capable of building things and getting things done, i.e. which are potential hires. It could also expose students to the types of work, and the style of working, that occurs at a start-up.