@Sherin I hope you haven't submitted anything yet!
I've asked for the traffic order but it might not come back until 11 June, however I don't think it matters too much. See these cases:
Roger Marlow v Royal Borough of Kingston Upon Thames (2170021610, 23 February 2017) (https://drive.google.com/file/d/1lEGiMYisrwPJkHb8oz-Qdq2CByNSeeSu/view)
Stanmore Quality Surfacing Ltd v London Borough of Brent (223050929A, 13 January 2024) (https://drive.google.com/file/d/1L3OEwynmO8a3iWg8Qs5pPSE8BlA_3Nl-/view)
Stanmore Quality Surfacing Ltd v London Borough of Havering (223050945A, 13 January 2024) (https://drive.google.com/file/d/1MEAhzT8Df7MWJhCskE7Fnl5KnqII0DQz/view)
Stanmore Quality Surfacing Ltd v Royal Borough of Greenwich (2240260573, 15 July 2024) (https://drive.google.com/file/d/1aw9Rf6MYyNsJHzsT3701sFaY2DcO_oFz/view)
Those decisions explain that the allegation of "Failing to comply with a prohibition on certain types vehicle" is inadequate because it doesn't tell you what type of vehicle is prohibited, so you don't know what the accusation actually is.
If there are photos of the signs on the PCN that remedies the problem, but in this case there are no photos of any signs on the PCN, so this looks like quite a strong ground to challenge the penalty.
Here's a simple representation:
Dear London Borough of Havering,
I challenge liability because the penalty charge notice does not specify what type of vehicle is prohibited, it therefore does not provide the grounds on which the council believes a penalty is payable. Because the penalty charge notice does not comply with the requirements of section 4(8)(a)(i) of the London Local Authorities and Transport for London Act 2003, no penalty may be demanded.
Yours faithfully,
Once submitted, take timed / dated screenshots of the confirmation page.