Hi, Andiamo, have just noticed you enquiry and whilst I am not familiar with your region of Italy, many of the plants that you grow we also grow here in Cornwall UK. I would suggest that you talk to your local nurserymen or the plant sellers at your local market (if you have one) Ask whether or not you could use camomile, which is the traditional alternative to grass, especially if you need a plant that is aromatic and the other I would suggest would be the low carpeting varieties of Thyme. With both of these, they will only stand a limited level of 'footfall' and depending on the size of the area, I have had great success in the past by adding slate stepping stones randomly to the area and planting inbetween, this will just ease the 'pressure' on the planting as people tend to walk mainly on the slate. As regards preparation, I would prepare it the same as if I was preparing a lawn; Remove or kill any existing weeds (spray with Glysophate-Round up) Cultivate the area, level and rake, removing any large stones etc. when you have a reasonably flat, firm, level surface which is free of perennial weeds and stones add a 2cm. layer of sharpe sand or fine grit (4mm to dust) and rake into the top 5cm. of soil, this will ensure that the winter drainage is good (a must for either camomile or thyme) The best time for planting would be in the spring and you would need to keep off the area until the plants are established.
I hope some of this is of use, best wishes Lannerman