Travelling back from Scarborough on a 140 mile trip today noticed a droning noise from the front of the car that changed dependant on speed (still there with clutch dipped and engine idling).

Only had new tyres fitted a couple of months ago and no problems until now so don't think it can be them.

Oddly enough when I got out to look the vauxhall centre hub cap was missing from the drivers side, can't imagine it's connected to the bearings/noise but seems wierd how both have happened at the same time

Any idea how much I'm looking at, got a 3.0 V6 if that makes any difference to cost and is it really safe to drive or am I likely to cause any other damage?