Is this normal practice?

Different garages have different policies as they are all franchises and can charge for what they like. Westover in Corfe Mullen for example, do not charge for a courtesy car for warranty work but do if your car is booked in with them for a service.

I think this is right. I dropped my Yeti into Grey Gables at Curbridge when it went into limp mode and was given a Fabia with no charge and no paper work. Mind you, they are a good dealer, so SUK are inevitably threatening them with closure. :(