Gave up on that Sonia Friedman link - payment wasn't being rejected, but the screen just froze every time I clicked 'buy tickets' and I didn't want to end up with £500 worth of tickets (just checked my bank and thankfully no money came out). Have just booked for the first Saturdays afternoon show through the Royal Court's presale, I will probably make a day of it and go and see another show or a film afterwards.
Oh I had hoped the "well over 3 hours running time" trend was going to be left behind in 2016. Never mind, I've got a few late night options for getting home. I'll just make sure to keep the next day clear for sleeping.