Advice for getting to the space and surviving your trip.
Get an Oyster card
Not having an Oyster card is a tax on tourists. A zone 1 single costs £4 without a card, but only £1.90 with one. The amount you pay is capped at the price of an equivalent travelcard, so unless you get one with your rail ticket, it's guaranteed to save you money.
A card is a £5 deposit and doesn't expire. You can also use it to open our door if you're a member.
Tips for travel from UK
Get the Oxford Tube from the High St to Victoria Station. It's slightly cheaper than the train (unless you're buying a couple of weeks in advance), and includes free Wifi and power sockets at your seat.
Walk to Victoria station for the District line, and change at Whitechapel for Hoxton. Alternatively, get the Victoria line to Highbury & Islington, and approach from the north. Both of these will take you on the East London line to directly outside the space.
The cheapest option is to get a Super Saver Return ticket for Greater Anglia services only. This will get you to Liverpool street station, from where you can walk (~30 minutes) or get a bus to Hoxton overground station which is directly outside the space.
You can also go to King's Cross and from there take the Northern Line two stops to Old Street, then walk (~15 minutes) to the space, or take the Piccadilly Line north to Highbury & Islington then take the overground to Hoxton station.
Travel from Cambridge station is about 1 hour 45 minutes via any of these methods.