First time dealing with car damage -- how to deal with this?

[Ippagoggy]

Bit inexperienced...

Front bumper got scratched while car was left parked on the street for a few hours (I'm guessing someone manoeuvred past it badly). The car is a long-term rental. I've asked a few repair shops for quotes and these are coming in at around 150-200 pounds from 3 different shops (sending them the photo and asking for a quote) to buff/sand/repaint. I'm thinking of just getting it repaired privately. However, as this is my first time dealing with this:

1. Do I need to tell the rental company?
2. Is there any point in contacting my insurance? It wasn't me, but I have no proof of that.
3. Can anyone suggest other things I need to think about?

Thanks so much!

Chips Away (they have franchises all around the country) are very reasonable for this sort of damage. Sounds similar to what happened to ours, scrapped it, putting in the garage. £192. Was about 5 years ago but might be worth getting a quote, you take a photo & upload it. Sorry I can't help with the other advice.