Don't waste your time with BY mate, gave them three years of my time, worked my arse off and they've just tried to screw us rejoiner's over with a new cointract which would see our seniority back to zero! Don't even think about getting a permanent contract if you join at a small base...you'll be stuck there till your dying day seeing as they won't give out any permanent contracts at small bases, BUT also won't transfer you to another base until you have a permanent contract at your base of joining.
Stick with MYT mate.