If things go wrong
Talk to the retailer first to try and resolve any dispute.
Explain to them why you don't think you should have to pay for damages to their stock. You may want to do this in writing and at a later date. They can't force you to pay up then and there.
If you can’t agree over payment, the shop could take you to the Disputes Tribunal, but they will have to prove you were careless.
The shop could choose to claim breakages on their insurance, rather than charging you for them. This will depend on whether it is worthwhile for them to do so. But their insurer may ask you to pay back anything they had to pay out to the shop.
It is also worth checking if your house and contents insurance will cover the cost of any damage. Check with your insurer.