That particular section doesn't appear to prohibit or establish fines for coasting.
I don't know about the UK, but I believe it's illegal to coast with the engine off in my jurisdiction, even though my car is programmed to do exactly that below 20mph.
Feel free to ignore any laws that are not helpful to society and are utterly unenforcable. If they are enforcable, it's fun to comply with the letter but not the spirit of the law, like so:
