Be confident.

Research who they are THOROUGHLY before the interview.

Have some questions ready to ask to show your interest in the company - they don't expect you to know everything, and wanting to know things is a really good impression to give.

Some good things to ask (IMO) is how your role fits exactly with the company (Council?) - what will your responsibilities be - saying that you're very interested in advancing your skills and what sort of training might be available (obviously this is contingent on the type of job it is - I don't know much about city planning!)

Be ready in terms of things like ... what do you feel your degree taught you ... what would you do in (x) situation (pays to put some thought into the skills you have that are applicable, e.g. in my last interview i was asked about how i would market product x and what i'd done previously to get out of a 'difficult' situation).

OK probably not much help but being able to articulate your STRENGTHS and having a 'weakness that isn't really a weakness' on hand are usually helpful.

VERY best of luck.