I can’t see you being left without a car due to a lengthy repair schedule but, Motability won’t want you in a hire car indefinitely due to costs involved. @Glos-Guy
I don’t know the answer I’m afraid, but my understanding is that Motability pledge to keep you mobile, so will provide a car for that purpose. I don’t think it should be a concern but best to call Motability if concerned. I’m sure that they will reassure.