Evergreen88 - If the cord is unwound or wound, it has the same length :-)
The Gene draws approx. 5.5A - That’s approx. 1300W at most, depending on the heating element. It even has an 8A fuse in it. I don’t know how a cord rated 13A would make any difference in this situation if I’m honest, but I’m no electrician.
Yes, the shorter the cord the better voltage you’ll have, but I’m not sure if it makes much of a difference in a 240V grid like the UK when using the Gene. I do know that in America (110V) that’s a common thing and it will make a difference.