Car resonating - possible wheel bearing gone?

My vRS started resonating last week - it sounds like it's got a naff aftermarket exhaust fitted once it goes above 30mph, however it's speed (not engine speed) dependent and would initially go quiet if I turned left (this change is now minimal). From what I've read online, I think it could be a rear wheel bearing (I don't feel any vibrations through the steering wheel so I guess not front), presumably on the left of the car because of the noise change under cornering.

Is there anything else that might reproduce the same symptom (speed dependent resonance), such as a heat shield or exhaust mounting coming loose? And how much should I look to pay to get it sorted? Any recommendations for a reasonable and reliable garage near Loughborough would be great too!