I also stuggled to find a plug, but I got there in the end thanks to helpful staff
Tiffin is definately the best!
The blueberry muffins here are so good!
Flat White has got to be the 'optimum' choice... Seats at the back comfiest and there's a power socket on the left hand side, learnt the hard way!
Has The Cloud wifi, free for o2 users / with registration (free)
Good, free Wifi