The Physics and Maths departments have their own separate library in the Physics building. And basically everything we need is right there. But I do know a few people who like to work in the main library sometimes.
And yes, they're in the process of being renovated. They usually do the serious stuff over the summer though, since there's less people using the building then.
Ah, but which beach...? There are two big ones, personally I prefer West Sands. Only because it's the closest probably...
And you can just email the main recruitment officer in the department, and either they'll be happy to take you around or can arrange someone else to do it. I've seen people taken around Physics on random days. (We sometimes like to joke that we should run up to them and tell them to run away whilst they still can....
)