It depends on circs though. e.g. I live in Germany but only speak English to my children. They learn German outside the home.
But I know a family where the mum is German, the dad is Portuguese, the parent's common language is English, so the child is being brought up to speak all 3, out of necessity really - neither parent is MT english, but it is their language of communication.
I also know an Afghan woman living in Switzerland who only spoke english to her dd. Sure, the mother and therefore the daughter didn't speak perfect english, but she learnt a very valuable language when she was moving internationally, so it really gave her an advantage.
I also know a mother who loves Spain, has a flat out there, and often, not exclusively speaks spanish to her dd. WHen they go to spain the dd attends spanish school, and I think she understands and probably speaks quite fluently, but understandably prefers to speak ENglish.
OP, if it is just to give your child the chance of growing up with a second language I've really now seen so many examples where is can and does work, and like I say, it depends on the circa. I feel, for example that living in Germany and the kids are fluent and learning German just fine outside, I think it's important for me ti only speak English to give them a firm founding in this language, but if you want to let your child grow up with a 2nd language, I would be very encouraging. Why not, go for it. I think even A Level standard is not good enough though, so in your case it has to be Italian, esp as you actively enjoy it. Good luck. It will also be hard work though.
i know I couldn't do it. I hate speaking German to my dc. It just feels so wrong. But then if I were living in UK and wanted them to hold onto their German, maybe I would feel strongly that we should switch to only speaking German at home.
I think the gift of another language if priceless.