I was surprised at the number of people who came to my clinic at Well Told who were also looking to attend day long workshops to get them up to speed on audio production.
Here are a few places that you could look if you want to improve your skills:
Transom is a great resource for everything relating to journalistic audio. From using music, recording interviews, interview technique, creating soundscapes and lots more. I use it any time that I feel a little lost with a project and need an inspiration kick.
Run by Cathy Fitzgerald, they provide weekend courses on documentary making and podcasting from a great creative mind. I attended an hour long workshop with Cathy at the London Podcast Festival a few years ago and would highly recommend her. Everyone I've spoken to speaks highly of her courses.
Karla Marie Sweet also offers courses sometimes. Again I attended a short session with her a few years back and it was really thorough.
I might look at running some one day courses myself in the future. If this is something you'd interested in drop me a line - it'll get the ball rolling a little faster.