I'm not overly keen on heights but I think I'd manage that.
Talking of heights, has anyone been to the Sky Garden in London? It's the 'Walkie Talkie' building near to the Tower and it looks like there's a fantastic view!
http://skygarden.london/Tom's in London this month (can't think if it's the 18th or the 25th) and managed to get a ticket, it's free but you have to book in advance and apparently time slots go quickly.