Fiat Ducato dash warning - check glow plugs

re Glow plugs ..... I'd suggest that your car is telling you that one or more of your glow plugs have failed or ... the relay that feeds them has failed. I don't know your vehicle, but there are cheap glow plugs & there are expensive plugs  .... the last plugs I changed were about £15 each but some have a 'pressure sensor' which are silly expensive.

As it's summer, you're unlikely to notice anything untoward, but as it gets colder you probably will.

(Glow plugs are a heater that get the combustion chambers hot to aid combustion, they generally only get hot to aid starting. Diesel engines are compression ignition vs a petrol engine being ignition compression)