Came across this mentioned in the Guardian so I registered and had a browse.
https://www.bl.uk/help/how-to-get-a-reader-passIf you do register there is a bit that says if you turn up at one of their reading rooms bring some ID - but for those of us nowhere near Yorkshire or London the reader pass lets you look at all the online stuff: I just spent half an hour looking at Charles Dickens hand-written drafts for Nicholas Nickleby.
If you've got time on your hands there is a lot of interesting stuff here.