With over 160,000 books, the Lit & Phil in Newcasltle is the largest independent library outside London and houses an outstanding music library. It is a public building so anybody can visit.
One of the posts on the Cambridge Music Librarians MusiCB3 Blog describes a visit to the Lit & Phil and recommends it if you're in the area!
You can find out more on the Lit & Phil website. If you want to visit, they say, 'don't be put off by the slightly austere facade and imposing entrance hall. Come up the stairs and into the library. The staff are welcoming and first-time visitors are always impressed'. Find out more about visiting the Lit & Phil. The library is at 32 Wesgate Road (NE1, 1SE), close to the railway station in Newcastle.
You might like to explore the online catalogue in advance, perhaps selecting 'subject' and searching for a book in an area that interests you or looking up a specific writer or composer. That way you can visit with a plan to research something specific, such as Mozart's symphonies or Milton's Paradise Lost.