Feel free to ignore my advice - it's worth what you paid for it.
When it comes time to analyse why your shots aren't working with long exposures and small apertures, think about how the exposure of lightning on the film is reliant solely on the aperture. The exposure is essentially instantaneous, so the exposure value on the film relies on the aperture and the film speed (a bit like flash photography). Trying to cheat the laws of physics is a mug's game, and you can't get bright lightning through a small aperture - no matter how long your shutter is open for.
Anyway, have fun burning film. It's the best way to learn. Stay safe ....