What was the cause of the leak please?
Do you know if the tenant reported it?
If that is right then you do have a claim against them.
It is all very well that you could claim upon insurance but that doesn't mean that the tortfeasor is not liable in law to you in the normal way.
Clearly a housing association is a defendant who can pay the award and the insurance company might well have sued them anyway.
This is perfectly appropriate for the small claims court arena.
Can I clarify anything for you?
All the best.