Hi Kelly,
Well a very large crowd (most of whom have been drinking in the many nearby pubs beforehand) gathers in Trafalgar Square on the run-up to midnight to celebrate as Big Ben chimes in the New Year. Its usually a great atmosphere around there - although you might receive a few hugs and kisses from complete strangers !.
Never heard of a 'Titanic' hotel though - are you sure that's the name? Who would think of naming a hotel after a disaster?!!
If you let me know the name of the show/restaurant you're going to (unless its a surprise from your boyfriend?) I'm sure that I can send you some links to reviews of them both.