London City I thought are only for business people with business prices. Isn't the train going to be a tad busy with all those people especially during the week where all of Canary Wharf are using them? Heathrow to Excel is a long slog on the train......
Car is easy ish to get to excel but you have the M25 to contend with.....
You really want the exhibition to happen on the M4/M3/M40 ....
Anywho I will only be going if there is a good enough reason but not for a jolly and going by past experience where my mate went in order to do some research in regards what products to buy then I won't bother, that's what PPrune is for.