Heat oven to 200C/180C fan/gas 6. Mix the crushed garlic and oregano with the lemon juice and 3 tbsp of the oil to make a dressing. Season. Make a few slashes in each chicken leg, then put the chicken in a large roasting tin and rub with 2 tbsp of the dressing. Stuff the squeezed lemon shells inside the body cavity. Roast for 30 mins.
Meanwhile, tip the peppers, onions, whole garlic cloves and courgettes into a large bowl, and toss with the remaining oil and some seasoning. After 30 mins, pile the veg around the chicken, drizzle with half the remaining dressing and roast for 1 hr.
Remove the chicken from the oven, lift onto a platter, cover with foil and leave to rest. Check the roasting tin, and if the chicken has rendered a lot of fat, pour it off, skim and return the juices to the tin. Stir the lemon wedges, mint, feta, chickpeas and remaining dressing through the veg and juices, then return to the oven for 10 mins to warm through. Pile around the chicken, scatter with mint sprigs and serve with bread, if you like, to mop up the juices.
