Here is Lee again having just driven from the 18th tee at Cumberwell. Not his best drive as his ball is still in the picture having come to rest a few feet behind where it was played from.
If this was 2018 Lee would be playing his second from there as it lies, but now, as the ball is still within the Teeing Area (a rectangle from the outer front points of the tee markers going back 2 club lengths), even though the ball is in play as he has made a stroke at it, he can re-tee his ball up anywhere within the Teeing Area and have another go with his driver. He will, of course, be playing two.
Note that the Teeing Area is only a defined Area of the Course for the hole that you are playing. The tees for other holes, or for other players on the same hole, are just part of the general area – so if you end up on a forward tee after your drive you can’t tee it up again there!