@Chewdog I'm sorry to tell you but I can't see any grounds that would justify risking the full £70 at the tribunal. You have admitted the contravention and on the basis of the CCTV footage, the contravention is made out in any event. There is a no-stopping timeplate here
https://maps.app.goo.gl/F36HucPRqx3MFMW28 and the only conceivable argument would be an issue around the camera authorisation, but it would be a gamble to appeal in the hope that the camera turns out not to be authorised or that there's some issue with the council evidence.
Of course if you want to appeal anyway we can help you with that, but at the moment I think you'd have well under a 50% chance of success so you may want to consider settling at the discounted rate.
The only caveat is that the discount is not meant to expire until 10 July so I would not pay before then. If on 10th July the penalty on the council website is still £35 then it's probably best to consider paying it.
If on the other hand it goes up to £70 at any time before midnight on 10th July, you have an open and shut appeal on the ground that the penalty demanded exceeds the amount due in the circumstances of the case (you'd just need a screenshot showing the amount due and another browser window showing the website
https://time.is/ so that there can be no dispute about the timing of the screenshot, this would need to be done on a computer and not on a phone).
Just make sure to put a reminder in your calendar and possibly an alarm in your phone for the evening of July 10th, as you don't want to miss the deadline.
