Just did the main halls on a Saturday when I got a window of opportunity (i.e. I was down that neck of the woods). Haven’t had the chance to set up a visit to the archives due to nature of my job, and this profile project deadline has been pulled forward quite a bit to try to support the organisation I’m doing it for (they would like it finished in two weeks). None of this has been helped by having the Car play up big time over the last few weeks.
It would be wise to ring in advance then if you want to visit the archives. I think their only open Wednesdays – although they made an exception in my case. You want to speak to Susan the curator, he number and email is on their website.