I had planned to visit but took me a while to spot the entrance! The queue when i arrived was really long, so i used the wifi at Nero coffee shop to purchase tickets online, much quicker! Once you get through, past the cloakroom, to the lifts there was no one waiting. The lifts are manned and you cant explore the rest of the office building as its one stop.
At the top there is lots more space than i remembered. A shop for souvenirs, a cafe, deckchairs to chill (but too low to sit and enjoy the view), and various telescopes to get a closer view.
It really does give you a great view of the whole city and beyong, with information boards so you know what you are looking at.
A great way to get to grips with the layout!