The shop knowing you would have to reach inside a rack where there are sharp edges which you would be unable to see to obtain the goods have a duty of care, the legal obligation is to take reasonable care to avoid causing damage. There is a duty to take care in most situations in which one can reasonably foresee that one’s actions may cause damage to the person or property of others. There is no liability in tort (civil wrong) for negligence unless the act that causes damage is a breach of care owed to the plaintiff.
There is a limit of £5,000 at present in the small claims court, which may well be increased this year, the small claims court is a misnomer, they do not sit in a court room but in a private room, they are not robed and do not insist on the normal rules of evidence and the atmosphere is informal and relaxed, they are more a service than a court. The judge is a district judge who should be addressed as Sir, not Your Honour.
The small claims court will have expected you to try to settle the matter before going to court which should be the last resort, I suggest, if you decide to proceed, you first speak to a local solicitor.