cutting it a bit fine if you want to do it this weekend arn't you?
Don't go with springs if you're unsure about ride height, as you're stuck with that you get.,
get a decent set of coilovers, and you can adjust the ride height to your hearts content.
If you just want to go low and look good, then things like JOM and cheapy stuff are OK, if you want it to handle well you're looking at at least £500 on something like the weitec Hicon GT's or perhaps the AP's at about £400. even then you're only just scratching the surface of decent suspension....