Part-time work is an increasingly significant part of college life for most students.
As a result, a number of colleges now operate part-time employment bureaux, usually attached to the Careers Department, while the larger SU's rely almost exclusively on students to work their bars and clubs.
Local papers - the Evening Telegraph(Coventry) - have special job sections on Thursdays, and local job centres hold part-time/evening vacancies.
High Street temping agencies such as Pertemps are also well worth investigating.
Students are usually offered silver service (waitressing), warehouse work, retail, general office / administrative duties (filing, word processing, data inputting) or, if you're lucky, IT based assignments, and agencies require a full CV, references, and may subject you to a brief typing test to ensure you can use a computer or specific package.
Don't be daunted by this as employers tend to like students, believing them to be (now don't laugh) resourceful, adaptable, and intelligent, and agencies can offer brief training sessions to get you up to speed.