So I've replaced the license plate today, and ordered replacements for the windscreen etc. which ought to come next week. I need to order a couple of extra bits I've just noticed - it turns out that part of the plastic "glass" of the speedometer has gone milky from the heat, and the second mirror is more badly damaged than I initially thought - but the total cost shouldn't be more than £150 or so, which will be considerably less than the cost if I actually make a claim.
But it's already street legal again, with the plate replaced and the mirrors temporarily fixed, so I've only had to pay for one day of public transport. It could be a LOT worse.