Welcome to FTLA.
As the notice has been sent so late, it may be prudent to check the car's V5C document to double check that it contains the correct name and address.
If your partner is the registered keeper, any appeal should come from them. As this is a station car park, it is very likely to be railway land, making it subject to byelaws. As a result, they have no way to recover this from your partner as the registered keeper. They can appeal along the lines of the below:
Dear Sirs,
I have received your Parking Charge Notice (Ref: ________) for vehicle registration mark ____ ___, in which you allege that the driver has incurred a parking charge. As Billericay Station is subject to statutory control in the form of byelaws, it is not relevant land for the purposes of Schedule 4 of the Protection of Freedoms Act ("the Act"). As such, you are unable to recover the charges from me, the registered keeper.
Even if the car park were relevant land, which is denied, you have not issued a Notice to Keeper in accordance with The Act, and it is now too late for you to do so.
There is no obligation for me to name the driver and I will not be doing so. I am therefore unable to help you further with this matter, and look forward to your confirmation that the charge has been cancelled. If you choose to decline this appeal, you must issue a POPLA code.
Yours,
If appealing online, be careful there are no drop down/tick boxes that cause you to identify who was driving, and keep a close eye on your spam folder for their response. If they do not respond within 28 days, chase them.