GNATS!!!!!

Hi all! I’ve just put in my winter veg last week and I’ve come home from the Easter holidays to find my beds completely encompassed with gnats! I added new soil and manure to these, plus the lucerne. What can I do to get rid of them? I think they’re killing my snow peas! Do i need to get rid of them, or they’re harmless?

I’ve had them on my indoor plants previously and just sprayed them with flyspray and that’s sorted them out, don’t really want to do that to my veggies.

Thank you!!