This sounds really upsetting and I think it would be reasonable to make a non-emergency report now—not as retaliation, but so there is an accurate record of what has happened.
Give the police a short, factual chronology and let them decide what is relevant: the hose incident, the cameras, your request that they be repositioned, the parking demand and now this letter. You can also offer them the recordings of the racist remarks, explaining exactly when and where they were made, so they can decide whether an offence has been committed.
Her letter is not an injunction. Only a court can grant one. I wouldn’t reply or knock on her door, though. Keep the letter, avoid direct contact and continue recording any further incidents. Obviously, report anything urgent straight away.
She cannot reserve a space on a public road for her boyfriend, assuming your car was parked legally.
The CCTV is a separate issue. Recording beyond her boundary is not automatically unlawful, but data-protection law applies if the cameras capture your garden, other properties or identifiable people outside her land. She should have a proper reason for the coverage, record no more than necessary and consider using privacy masking. You can ask what is being recorded, object to being recorded and request footage in which you appear.
Normally, you would raise those points with the camera owner before approaching the ICO. Given her demand for no contact, I would ask the ICO how best to proceed before writing to her again.
This explains the CCTV position and the practical options:
https://thesilverbrief.blog/neighbour-cctv-disputes/
Full disclosure: I’m connected with the site, but the article addresses this precise issue and links to the relevant official guidance.