Welcome to UKCS.
If there isn’t a deluge of suggestions, use the site search here, tick for open all year (and anything else that’s important) and probably on-site bar or restaurant. Then check their websites or FB pages.
You might also want to check for towns having parties, that you can walk to from the site. I knew of at least two towns up here that have street parties or beach BBQs; they’re too far away for you, but there might be something similar in the NW.
Good luck.
Holgates have a number of caravan parks in the north west and they usually do family events for various annual occasions. For example, we were at Bay View last weekend and they had a bonfire, fireworks and BBQ for bonfire night and children’s activities such as a pumpkin hunt, halloween fancy dress completion and seasonal crafts during the day. I am sure they will have new year stuff going on. Bay View is their quieter site but if you want somewhere with a pool etc, look at their Silverdale site.
A day of all things motorhome and campervan. The show is held both in the main indoor arena and across the grounds. Catering, hot drinks and food options are available. Easy access to the site and free parking included. Win one of five pairs of day tickets