Scuba detection in shallow water is not so difficult, but passing at least a level of certification will help you to understand the buoyancy and the material technical aspects.
For Italy, prefer the CMAS level 1, last choice will be the very basic PADI Open Water. Try to have at least 15/20 dives beforescuba detect alone.
Keep in mind, scuba detection from the beach/coast is physical, everythings heavy. To detect in less then 5m (17ft) you will have to carry a lot of extra weight. If you use a 7mm wetsuite, it'll be around 14 to 16% of your weight to be confortable.
When you have have finished and you want to get up after 3 to 4 hours of underwater detection, you will feel how russian astronaut can suddenly realized how HEAVY they are
For the little story, my detecting mate AQUAMAN didn't had any land detecting experience prior to scuba detection. We had the opportunity to use our detectors on land almost a year after he started to scuba detect... he was supprised how easy it was...and most important how easy it was to pack everything and go home.
Last thing... prior to dive, take a few minutes to have a look to the sand condition in apnea. Once you've put your tank and with all the weight you will carry, you are not going to move so much or take your car for another spot.