Hi I was wondering there is no rules or actons to goven turning a ship, speeder or other, Around

eg a Firespray is coming up behind a Ywing but the Ywing needs to turn round to be able to fire its weapons what acton manvnr govens or is it a case of using your manv for the round

The ship combat system isn't a tactical simulator with every move being dictated by a rule. So the easiest answer is the Y wing just does when it comes to be their time to fire in the initiative order. The system just assumes there is a considerable amount of ducking and maneuvering going on during the course of battle that you simply narrate rather than roll individual dice for and utilize specific turn mechanics and such.

Yeah, this system assumes you know how to "not crash" while trying to do other stuff. So a gunnery check already includes the assumption that you are also making the proper turns and maneuvers to line up the shot. Facing doesn't really matter* since what shield zone you hit hasmore to do with maneuvers than actual position.

*except when it does. Against large craft you are expected to track which side you are on and a fly maneuver is needed to move from one zone to another. In the realm of fighter combat fire arcs are about what you can bring to bear. So if say a y-wing pilot shoots the lasers at a group of ties, the copilot/WO can't shoot the torpedoes at a different group, but he can turn the ion cannons at whatever he likes.