I strongly advise using a gui such as Tk. Sure there is some learning to do, but the amount of code involved is likely to be much less and more directly pertinent to providing the UI than anything CGI based. There is a larger disconnect between code and effect in CGI than using a gui like Tk which makes the creation of the code and debugging it harder.

Heh, maybe there's your science project right there - test the assertion that a Tk based gui is easier to develop than a CGI based one. Metrics in terms of time spent, lines of code, perceived difficulty, ease of maintenance, ...