If you are coming from Nairobi you'll need to get to the Likoni Ferry crossing in Mombasa.
From Likoni Ferry Galu Inn is roughly a 40 minute drive. Keep going straight for about 35KM and you'll come to a right turn just after Diani Hardware Store. Take the turn and continue for about 2KM to the Nakumatt supermarket junction. At the Nakumatt supermarket take a right and keep going straight for around 10 minutes (on your left hand you'll pass Robinson's Baobab Beach Resort, KFI Supermarket and Almanara Luxury Villas). Galu Inn will be on your right directly oppositte Tamani.