Katia,
Isn't there a way to actually get out into these communities? You're studying in Scotland, right? How far away are you from the communities? (Assuming they have some established communities).
The reason I say that is because I think Italians, in general, respond better to more personal interaction (ex: connecting with the local shop owners, coffee houses, barbers, etc. and trying to meet face to face or at least through known, trusted people vs., say, posting something on the web).
If there's any POSSIBLE way to do something in person- or even by phone if you have to- I think you might find more success in your recruiting.
If there aren't many established communities (like 'Little Italys) then you may have to take another route. Such as: finding restaurants that they eat at, etc. Find some place where they congregate and network through there. Ask the local owner for help. He / she may be willing to even take a stack of surveys and get regulars to fill them out for you.
Italians, as I'm sure you know, can also be distrusting of institutions, higher education, etc. due to their history. So going through someone that they trust may also help your efforts. In other words, recruit someone to recruit for you!
Last but not least- make sure that you express what's in it for THEM. Why should they do this? Prepare a short one or two sentence statement of why you feel this work is important (make it something that THEY will care about).
I used to be in sales, can you tell?
That's just my 2 cents. You may have tried some of these things already but I thought I'd throw it out there just in case. Good luck.