Hello! I'm looking for black boots...I'm a teacher and already know that I will be outside at least once a day next term so I need something that looks semi smart for inside and practical for outdoors. I usually wear skinny/slim trousers to work. Ideally I'd like leather and boots that are not too tall. Maybe lace up but not too chunky, not DMs. I'm a size 7. Not sure where to start, I usually buy from Next. Thank you!