In the grand scheme of things, (and I don't wish to belittle the injury you suffered) you have suffered a realtively minor injury and it is unlikely that a law firm would take on such a case as it has to be worth over Â?1,000 for solicitors to be able to claim back their costs.
On top of that, it would also have to be shown that the owners of the bench (local authority) were negligent in that they were aware of the potential danger and did nothing about it. This could prove to be costly and not effective.
If the injury gets worse, then the situation may change and it could be worth looking at, but for the moment, reporting it to the council is your best most sensible option.
