As far as the spelling errors etc are concerned this isn't a marked and graded website ,
well someone told me if convicted on byelaws it doesn't get put on your CRB
Also I had £2.80 on the card it cost 0.75£ on 16+ oyster as soon as the officer let me go I tapped in and left I didn't top it up because there was sufficient amount.
Anyway thanks all even the guys who like to bring my integrity into it
Ignoring all the chitchats, I get the impression that either you are not fully appreciating the severity of your actions, or you are not taking this very seriously at all.
With regard to your previous records, there is only so much people can try and suggest you do each time this sort of thing happens, and everytime you do something like this, your options will reduce. Eventually you will run out of options and they will put you in jail. I am not scaremongering. I fear that if you cannot learn after paying £300 to get yourself out of a sticky situation, there is not much that can make you learn. So for your own sake, next time, if the gate does not open, don't push through it, ask a member of staff for help. If you have a habit of running late, leave yourself a bit more time so you are not always in a rush. If you miss that train, waiting half an hour is better than your pocket being several hundred pounds lighter, or worse.
So back to this matter in hand, as others have mentioned, you don't really have any ground to challenge it, so plead guilty, pay the fine, and make sure you don't play with fire again, that is, if you want a clean record for the sake of your future career.
(I also have questions over the legitimacy of your 16+ card, but since you did not bring it into the question, I am not going to ask. I make the assumption that it was used legitimately. If it were a factor in getting you in trouble this time, things may not be so easy.)