possible low pads , does the noise lesson when braking or increase??
,, some cars have early warning l bits fitted , they make a horrible sreaching noise
its to warn you pads are getiing low and to change them..
.as above could also be wheel bearing ,,
if you get the pads checked out and there ok i would get it looked at ,,before any long journeys ,.
also check powersteering fluid level isnt low ..