Do check with the club.
Not Snell certified does not necessary mean it is not compliant, if it is also ECE 22.05 certified, you should be good to go. FYI AGV helmets that VR race with in MotoGP is not Snell certified, iirc all AGV helmets are not, but they are ECE 22.05 certified, therefore good enough for MotoGP and your local trackday.
On the other hand, Snell certified may not necessary mean it is compliant either. Some clubs will only allow Snell 2005 or newer, so if you have a Snell 2000 it will not be compliant and/or if the the helmet’s is too old (manufacturing date), they might not pass tech either.
Hope this helps or confuse you even more…:rofl