Hi Hannah
Have you tried Butlins at Bognor Regis?.....they do have 3 night stays there over the New Year period.
It may still be a bit early for most hotels/pubs etc to advertise their NY party plans, so my advice is look around for a nice family pub or a hotel, that may be having a bash on NY's eve....many do.......and caters for young ones..... in your area around Portsmouth.
Ring around some family pubs and if they get enough interest, some even lay them on...........or community centre's...........church halls........etc!
I am on the south coast near Brighton.
I have four little cubs, and as i'm a dj, i play away from them most years, as i have to sometimes play clubs....this year i have a function provisionally booked, with all family -one, booked to play in Surrey, at a hotel, so am taking mrs bear and the little cubs with me.
Best of luck in finding one, hannah
and take care.
love the bear x
:0)