Hey Alessio,
I can also totally recommend Mr&Mrs Gluten Free, I go there whenever I can and they have the broadest (and best imho) selection of gf products in Switzerland - they also have frozen stuff, which is extremely uncommon here.
On top of the classical supermarkets and Mueller, you may also look at
- Egli, in Zurich HB, having also some good pastries
- Ultimo Bacio, close to Wipkingen, a bio shop with some gf items. Beware of the fresh items though: I was once there and I remember a fresh "gluten-free" pastry in the middle of normal pastries, so contamination likelihood was 100%...
If you are looking at online opportunities to buy, this is this meta-website with a couple of very useful links to shops that ship to Switzerland:
http://glutenfreiheit.org/shopvergle...ortierung=name
Finally, as you already know being Italian, a week-end in Italy by car might be extremely useful to refill the kitchen with variegate and good stuff at the same time arbitraging a bit on prices - the Esselunga in Varese is a good example of a place where I spent quite a bit of money!
Even if not asked by the OP but only later in the thread, there is an official list of "certified" gluten-free restaurants from the Coeliac Association:
http://zoeliakie.ch/images/PDF/2014/...astroliste.pdf
Please note that they update the list quite often, so the link might become obsolete soon but the new link can be found from the homepage of zoeliakie.ch
The other source of information I use to search for gf restaurants, though not necessarily certified, is this website by Schaer:
http://www.glutenfreeroads.com/en/
Hope it helps!