When Hayley Atwell was 13 she wrote a couple of letters to her future self. The one she opened first, aged 18, read, ‘Have you won an Oscar yet? Are you married with children? Have you published your first novel?’ And there was another one, to be opened when she was 40. What did that say? ‘Hmmm,’ she says. ‘I’m not sure where that one is now – I’ll have to ask my mum. But whatever is in that letter, I don’t think it was written with the expectation that I would be sitting here talking to you abo