Hi,
I'm currently a student in full time education... as far as entrance criteria is concerned, it depends on two things 1) the course 2) the university. A good site with the full range of university courses would be
UCAS
These people liase between secondary schools and the universities for people to transistion from A levels to their courses. I don't know if they help with mature students or not but they'll always help if you give them a call. If not, call the Admissions office at any of the uni's that have a course your interested in. Another source of information would be your Local Education Authority that will be found at your county council head offices.
In case you're not aware a sandwich course will involve four years full time study, with one of those years usually the third , being a year working in industry to gain experience....
Hope this helps, any other info needed just shout!
C