You are really trying to get this PCN cancelled before it hardens into a full £160 liability, because that forces Lambeth to prove the case.
Your best challenge is twofold. First, "the contravention did not occur", meaning Lambeth must satisfy the adjudicator, on the balance of probabilities, that your Kia entered the priority section when the oncoming vehicle was close enough that you should have yielded. There is no fixed distance rule. The adjudicator will care about the exact moment your car committed, where the blue vehicle was then, and whether it had to slow, stop or give way because of you. The speed hump point only helps if it affected sightlines or made the priority arrangement misleading.
Second, "the penalty exceeded the amount applicable", meaning the council used the wrong amount or wrong legal timetable. Your PCN shows a notice date of 27 March 2026. Lambeth says moving traffic PCNs are £160 reduced to £80 for 14 days, and London Tribunals says representations must be made within 28 days of service and that this ground covers the wrong amount or a defective PCN process. If the portal is using the contravention date of 20 March to say the case goes to £160 on 16 April, that is a serious point because the council cannot substitute portal dates for the statutory dates.
On the driving evidence alone this is arguable. Add the date defect and prospects become realistic. If the CCTV shows the oncoming vehicle braking or waiting for your Kia, the merits weaken fast. If the portal screenshot is incomplete or turns out to be a display quirk, the procedural point weakens too.
Do you have the CCTV and a screenshot of the portal page? Are you prepared to risk the discount to go to tribunal if Lambeth rejects? Would you take a re-offered £80, or is cancellation the only acceptable outcome?
Make formal representations now on both grounds, attach the PCN and portal screenshot, and say the portal misstated the lawful dates so the penalty exceeded the amount due. Do not pay if you are challenging. If Lambeth rejects, appeal to London Tribunals within 28 days of service of the rejection.