ruth wrote:

He will plead guilty, to avoid hassle, but he isnt guilty because I
told him he could use my ticket, and he being from up north didnt know
any different.

No, he's still guilty. That is not a defense.

I do not want him to get a criminal conviction or huge fine because he
doesnt deserve it.

Probably too late for that. The best you can do is to call up the
prosecuting agency (probably TfL?) and try to plead with them to drop
the prosecution somehow. I wouldn't hold out much hope though.

The court have only given him 1 week notice before the case,

It's one week before he has to make a plea. If he pleads not guilty, the
case will be adjourned for a trial at a future date.

which is pretty ****e, so we have no time to get proper advice.

Nonsense, criminal solicitors are available for consultation at very
short notice.

he was technically guilty, because he used my pass, but the
fact remains he didnt know he couldnt use it..

Do you think a magistrate would believe that? If so, then you can plead
not guilty. If not, you should plead guilty and add this information in
mitigation.