The benefit of a tin roof is that it is difficult for embers to enter. The only points of weakness are (normally) around the edges: top ridge, botton edge (near the gutters).
So it pays to seal these areas properly. When fire is possible, folk here are advided to block the down pipes and fill the gutter with water, this stops embers collecting and working under the tin.

Its embers entering the house, esp the roof space that cause many houses to burn, although strong radiant heat, or actual flames will burn it too.

Some people install smoke alarms in their roof. You should make sure that you have a ladder in place so that you can check up there for any embers, and an extinguisher at the ready.

Don't count on municipal water pressure if you are at home during a fire; all you neighbours will have their hoses on and any fire trucks will be hooked up too; and if power fails (as it often does) the pumps which keep the water pressurized will proibably fail too, so there will be no water.

Best practice is to have your own pump with plenty of fuel and a secure water supply like a pool or fireproof water tank/s.

Good luck Blast, but I hope you don't need it !