Can you give me some advice about suitable vegetables to plant in a coastal, south-easterly, windswept plot?
If possible, try and create some shelter for your coastal garden. Given the conditions that you describe, whatever you choose to grow will be slow growing and quite likely to suffer some physical damage.
Windbreak material firmly attached to strong stakes takes up very little room in the garden and can make a marked difference in your vegetable production.
Vegetables that will be most hardy, given the conditions, should be lower growing to avoid physical damage from the strong winds. These vegetables include; broccoli, cabbage, cauliflower, carrots, leeks, onions, silverbeet and spinach.
Regardless of your existing soil, add in generous amounts of compost prior to planting and mulch during the growing season with additional amounts of compost.