Preheat the oven to 180°C/fan 160°C/gas 4. Break the ciabatta into roughly 1cm pieces to make croutons, and then scatter them onto a baking tray just big enough to take the croutons in a single layer. Toss in a drizzle of olive oil and break/crumble the feta into large pieces over the top. Add a little oil over the top of the cheese and season with pepper. Bake for 5 -10 minutes at 180 degrees Celsius until the croutons and feta are just beginning to turn golden.
Place all the dressing ingredients in a screw-top jar and shake well. Peel the cucumber and slice it in half lengthways. Scoop out the seeds with a teaspoon, and then cut the cucumber into chunks. Mix the cucumber with the tomato, pepper, celery, onion, olives, basil and parsley. If eating straight away, add the ciabatta and feta croutons, and toss everything together with the dressing. If eating later, keep the ciabatta and feta croutons, and dressing separate from the rest of the salad and mix together when ready to eat.