My (parked) MK2 was hit by a Waitrose delivery van ~3 weeks ago (see picture). The damage doesn't look too awful - although I cried when I saw it - but I am having a complete 'mare with the insurers.

John Lewis' insurance broker initially said it was a write-off as the offside rear light alone cost £850 (you have to buy a pair). Then they mentioned Lexus 'black lights' they could fit for less, and maybe give me a contribution towards the OEM parts so I could try and source them. Now they say that even the back bumper is nearly impossible to find and they might order one that doesn't fit right so they don't want to take the risk. They'd rather give me a (poor) cash-in-lieu settlement and wash their hands of it - letting me take the risk instead.
Questions I would be so grateful for your help with, please:
1. Will I likely be able to find an offside rear light unit for my car (its an anniversary edition)? The insurance guy says no and I know I'm at risk of being ripped off if I try and just find something online. Apparently offside lights are harder to find than nearside and you can't get OEM parts even from Japan.
2. If I had Lexus lights fitted, would this be a big no-no for anyone I wanted to sell her on to when I can't maintain her any more? I have no plans to sell her now. I paid £2.5k to have her resprayed 18 months ago, but I really don't want to decrease her value by using non-MR2 parts. I have worked hard to keep her in good nick (I've had her 20 years).
3. With a car this age, would a normal body shop be okay to do work on her, or should I be looking for a specialist? The insurance guy is saying I could broker a deal with the garage my car is currently with, but I don't know this garage at all and have recently moved from London to Herefordshire (since they hit my car).
I am up a creek without a paddle with no car and no idea what to do next.
If you chaps can offer any advice, I would be incredibly grateful.
Jo