'When can you start?'

Well well well, it would appear that the Gods of good interview technique are favouring me slightly more than usual. I normally find myself in the worst frame of mind to be interviewed when I'm knackard and yesterday I woke up with fifteen minutes to get myself there, looking relatively immaculate. I did a Mr. Bean style getting ready and parked my car like a total goon before opening the door and walking in the second the clock struck ten. I had, in my haste, not quite coordinated my shirt and trousers properly; by this I mean I had zipped up my fly with part of my new shirt wedged in it. So I shook hands with the manager not realising I had a tiny fin of white shirt flapping around out of my flies, a mistake that once realised, was hard to put right without looking like I was doing something untoward unfer the interview table.
I'm also always at a loss at which stance I should take when in interviews for jobs that are slightly more menial than others; by saying 'I'm a graduate and I eventually want to go into teaching' I feel I'm making myself sound overqualified. Its a bit like Peep Show where Jez is in an interview for the cleaner's job at the gym and the dialogue goes something like this:

BOSS: You say here that you're a graduate. You know that this job is very long hours, for very low pay.
JEZ: Yeah, I dont mind though. I like that.
BOSS: You do realise you'll be doing things like mopping the floors, cleaning the toilets and pulling the hair out of the plugholes.
JEZ: Its ok, I think its interesting.
BOSS: Its not interesting.
JEZ: Well, I'm still happy to do it.
BOSS: Are you writing a novel or something?
JEZ: (Thinks) Dont want to sound overqualified What's a novel?

The good news is that I got the job and I had the chance to start immediately that evening, little did I know that I'd be being trained up on the floor rather than behind the bar. I made nearly £15 tips tho, so that'll pay for a pair of inner-soles for my shoes (which are KILLING me!)
Got another floor shift today: just gonna smile, be polite and get the basics right. Anything else is a bonus.