[Closed] Shiplap building - securing and insulating for bike workshop?

Possibly moving to a new place, no brick garage so looking at converting exist out building for bike tatting and storage. Single garage size, timber frame with shiplap and double doors on one short end, one long side is half open. No older than 6 years. Seems to have elec supply.Couldnt make out what the floor was open rafters and joists. Any thoughts on how best to go about making it secure, insulated and lit for minimal cost? happy to block double doors off internally but will need a door where open section is. Not too fussed on a high finish inside, I'm thinking plywood will be fine.