The normal way to get from the airport to Freetown is the ferry. It's much quicker than the drive around the estuary and was fine the last time I did it.
UK government travel advice says this: "Lungi airport is situated on the far side of a wide estuary from Freetown. There are several transfer options from Lungi airport including by road, ferry, water taxi and local boats or pirogues. The 3 main water taxi operators run reliable services, with safe vessels."
Several decent hotels in Freetown. The usual travel sites will advise you.
If not, the only option is the Lungi Hotel as the other place burned down.