I've been getting this squeak, much like brake squeal from my vRS of late.

The sound starts right after I have applied brakes, and continues as long as the speed is low. It goes away at high speed. The sound increases if I keep the wheel slightly turned to the right.

Any ideas what it could be?

Pad sticking, heatshield rubbing or a stone caught I would think.

feels like pad sticking to me.the pedal is soft unless i give it a solid press.does a caliper need changing?

It's probably just the pad sticking "on", which leads to it getting hot, and hence heating up the brake fluid, giving your soft (also long?) pedal. Get some brake cleaner, and get the brake dust out of the pad guides. If you understand this from the statement, maybe use a little copper grease on them too.