Hi guys,

So I have a little work function on this Friday and to my surprise I have been approached to be the photographer for the evening.
Now at first it was a bit daunting but I'd really like to give it a go. Its not a huge formal function, more of a get together so I don't need to be a professional

Now my problem. I have no flash (other than that on my D3000 which is not that great).
So I'm looking at some advice before I commit to the task.

My setup is pretty basic. D3000, 18-55mm lens (I believe this will be good enough?).

I've been looking at the SB-600 but it is very expensive in Canberra. Ted's want $450 for it! So I'd like to know if it is worth it or should I look somewhere else.
Also would I need a diffuser?

I will be shooting in dark lighting (ie in a club) and it would be mostly close up portraits (shoulders +heads) to maybe some group shots (5-10 people). And this is also what I would focus on in the future.

So any advice would be greatly appreciated The more the better.

Thank you,
Chris