Welcome to the forum.
A cable release is not needed but it sure would come in handy. A tripod would be really helpful as well.
If you are trying to capture lightning when it's completely dark, it will be much easier because you can basically leave the shutter open and hope that lightning strikes while it's open. If it's not too dark, you can only keep the shutter open for so long before the film gets over exposed by ambient light...but if you can get some nice scenery with a lightning stirke...it would be a much better photo.
Another method would be to just leave the shutter open and cover the lens with a black cloth or card. Then remove the cover when you think lightning might strike, then cover it again. You can do this repeatedly to get multiple strikes at one time.
It's pretty much an experimentation process...so try different things. But be careful...don't stand out in the middle of a field in an electrical storm.
I would suggest using ISO 100 film.