Buttermilk Marinated Chicken

Somehow, just the name of this dish feels comforting to me. Two very homely, somehow old-fashioned words butter and milk and then of course the family favourite of chicken, make this a very warming, hearty meal. However, one less comforting thing is that buttermilk itself is fairly outdated, so is a little expensive, but should be in most supermarkets. If you can't get it, just thin out some natural yoghurt with milk.
Marinating is something I wouldn't usually do- it seems a bit pointless and I'm a huge last-minute-larry, but given how tender and flavoursome today's chicken was and how easy the meal therefore became, I've decided to integrate it into my everyday repertoire.
1)In a large dish, combine about 750g buttermilk with 1 tsp paprika, 1 tsp dried thyme (you could use any dried herb you want) a good tbsp salt and coarse pepper, 1 tsp dijon mustard, 1 tbsp vegetable oil, the juice of 1 lemon, and throw the husk in afterwards and 4 peeled garlic cloves, broken by crushing them with the side of the knife and pressing with the heel of the hand. Coat and smoosh 12 chicken pieces- I recommend skin on, bone in chicken thighs and drumsticks, although you could spatchcock a whole chicken. Let it marinade overnight in the fridge.
2)Take the chicken pieces out, and place them in an oiled roasting tin. Throw the pieces of garlic in with them.
3)Roast them at 220 first, for about 10 minutes, then slowly roast them at 180 for about 40 minutes. Remove excess liquid with a turkey baster or by tipping out into the sink periodically whilst they're baking. To check if they're cooked through pierce the biggest thigh with a skewer and the juices should run off clear.