A rather good summary of the radio waves coming from lightning:
He does mention the Inspire VLF-3 radio kit, which you can order here. A neat kit, although it’s admittedly a bit pricey. But, it is complete with PCBs, discrete components, and instructions. You need only add a soldering iron. If you’re looking to explore more than simply QRP transceivers, it’s a good step in the exploration.