The relevant legislation states that "During the emergency period, no person may leave the place where they are living without reasonable excuse". It then goes on to list specific circumstances which automatically qualify as a 'reasonable excuse' (such as obtaining basic necessities or obtaining medical assistance) but the list is non-exhaustive. i.e. there may be other circumstances, not contained within the list, which a court might determine to be a 'reasonable excuse'. For example, if the only way that an NHS doctor (or other key worker) can get to work is by car, and his car is no longer serviceable, it would almost certainly be regarded as a 'reasonable excuse' for him to leave his home in order to seek to purchase another vehicle. So not everyone would be prevented from viewing your vehicle but many (and probably most) would be.
Similarly, you'd need to be able to show that you had a 'reasonable excuse' for leaving your home if you were to seek to purchase a motorbike.