One of the problems with growing courgettes (or zucchini if you prefer) is that at this stage of the late summer you find that you have more courgettes than you know what to do with. The usual view is that you cannot freeze them successfully, however in my experience this is only partially true. First of all freezing works best with smaller courgettes as the larger ones contain too much water. Secondly, you may find that for some cooking uses the flavour and texture of your previously frozen courgette is, frankly, a little bit weird. However, for roasting in a little olive oil (cooked from frozen) the taste and texture is indistinguishable from fresh ones.
What you need to do is slice your courgettes (about 1/2 cm to 1 cm thickness) and spread the slices out over a metal baking tray and put in the freezer. Once your courgette slices are frozen then remove from the baking tray and put in a freezer bag. They keep for about six months.