Below, I have created a list for those that are interested in book publishing opportunities. I will be updating this page with new links frequently, and if you would like regular notifications please 'subscribe via email' on the homepage.
Feel free to contact me if you'd like more details or if you'd like to contribute to any of my 'Intern Opportunities' pages.
http://www.anthempress.com/internships
http://blakefriedmann.co.uk/work-experience/
http://www.pickeringchatto.com/contact-us
https://www.orionbooks.co.uk/Information/Careers.page
http://endeavourpress.com/contact-us/
The links below will provide you with useful links and tips. The fourth link will contain personal email addresses of book publishers within large companies. I discuss more about the importance of email addresses in my blog post 'Top 5 Tips to getting work experience'.