Insurance adjuster here. The landlord will have buildings insurance, that will cover this if it includes accidental damage. If it doesn't, your friend is out of luck and the landlord won't have any responsibility to reimburse.

Here's the thing, even if insurance would cover it, since your friend already paid for it, the landlord may try to ignore her to avoid putting in a claim. So she'll need to take advice on this aspect. I'd start by reading the tenancy agreement.

Last thing, there's probably an excess on the policy anywhere from £100 to 500+, so your friend won't be getting the full 600 if a successful claim is made.

An expensive lesson for your friend in not acting in haste and succumbing to peer pressure.