Sorry in advance as I'm not intending to be rude or critical personally here.
BUT, if someone moved onto our street and took it upon themselves to host a party for all the neighbours for no obvious reason other than that they'd just moved in, I'd be quite wary about who had just moved in. To me, it's screaming "attention seeking", "look at me", etc. I think I'd try to reserve judgement until the day itself and saw what kind of event it was and who else was going, and then maybe just pop in for a short while only, maybe for a drink, rather than staying the whole duration for a meal etc.
It may be an age or background thing, but my road is pretty quiet with everyone keeping themselves to themselves. We're all friendly enough over the garden fence or passing in the street and pass the time of day, but we're not "engaged" in eachothers' lives and aren't in and out of eachothers' houses. None of us (except 1 see below), ever have parties etc - maybe just a handful of friends or relatives for New Year or a Summer barbecue or a birthday, but certainly not "open houses" for the neighbourhood.
Not saying we're right and you're wrong, just saying it as it is on our road!
Now, our 1 neighbour who does have parties. She's a pain in the arse. 100% attention seeking twat. Ever since the day she moved in, she's had big parties virtually every month. She's "the one" who leaves her teenage kids alone to have all night parties whilst she buggers off to leave the neighbours facing the noise, damage, chaos etc. When her kids were small, and all their friends were having parties at soft play centres or small parties at home, she'd invite the whole class to her house. Now they're teenagers, she's the one who insists on a dozen or so of her children's friends to come to her house for "pre-prom champagne". She's the one where her daughter's friends all come to change into their tarty outfits prior to a night clubbing and then all return there in the early hours in taxis with loud door slamming, shouting, etc.
I'm not saying the OP is like that, but it's that that makes me wary of someone moving in and the first thing they do is host a party.
Not everyone is social. A lot of people hate socialising.
I may be wrong, but I suspect the OP is either relatively young and accustomed to the social/partying lifestyle of university, or come from a different ethnic background (other than conservative English) where socialising/parties are more the norm. Not saying anything wrong with that. But the OP needs to realise that not all her neighbours are "into "partying and socialising like that. Just as much as it's unfair for the neighbours to assume the OP is some kind of noisy party animal, it's also unfair for the OP to criticise her new neighbours for maybe not wanting to join in with her party lifestyle.
As I said at the start, sorry for any offence, etc., it's not my intention, but just to put across an alternative view point.