In regards to prepping these for entertaining, your prep ahead tip is to parboil them a few hours before, cut and season them, and pop them in the oven once your guests arrive. If you are also doing the lamb, the potatoes can go in as the lamb is resting, before it goes in for its last blast to warm through and crisp up. If they’re in the oven at the same time as something else, they just won’t get quite as crisp but don’t sweat it.