S-line springs on my A3 1.6?

In theory it should. I'm no expert but I think it depends on what engine S-Line it was from. I still have my standard S-Line springs (sitting under my bed, ha) but mine is a 2.0T so assume will be slightly stiffer than S-Line springs off say a 1.4/1.6 because the engine weighs more. Plus you have Quattro models to consider too as they weigh more. I'm happy to sell you them for a silly price if they fit.

Let's wait till an expert comes along....anyone?!!

The struts on a 1.6 are 50mm where a 2.0 s-line are 55mm, so the springs might be different, I'd recommend getting some coilovers anyway.