London - New Years Question

The NYE Fireworks are a ticketed event.

Yes, now a ticketed event. Mayfair is good as you could walk home from any festivities.

If you do buy tickets, only £10 each, make sure to choose a viewing zone on the North side of the river, as you cannot cross the river locally if viewing from the South side and trying to get back to Mayfair.

Best tickets are in front of the Eye of course, but they sell fast.

If the weather is bad, which is possible/likely, you can abandon the £10 tickets and do something else.

I've not been myself, but i understand Primrose Hill is quite a gathering point on NYE, especially if clear and pleasant weather. You might not see much of THE fireworks, but will be plenty to be seen and you could even take your own small ones (easily purchaseble around town) and let them off SAFELY in the park with a bottle of Prosecco. Likely to be many there doing the same.

and let them off SAFELY in the park with a bottle of Prosecco. Likely to be many there doing the same.

I don't think letting off fireworks with a bottle of Prosecco is considered safe!

Fireworks first, then Prosecco, perfectly safe if you're a sensible adult. Not everyone needs the health and safety police to crush their fun.

To watch from a distance, try Sky Garden. You would have to have drinks up there, or make a reservation for dinner. Take a look at the photo at the top center of the page. If possible, you'd want to be on the outside balcony with your place to stand against the rail staked-out ahead of time.
https://skygarden.london/
Check the website to see what you'd have to do (reservations) to be up there.

Great post as I'll be in London for NYE too. I was thinking about the fireworks but decided it will be too cold and crowded for us (based on some excellent feedback here!). Still trying to decide what we're doing so thanks everyone for the suggestions.

We're staying in Earl's Court - any other suggestions about that area are welcome too!