I got married at the end of November, gloriously sunny day, whoda thunk it?! Everyone I invited came except my now FIL, who lived 5 miles away but couldn't be arsed (Oh yeah and my BIL but as he and my DH don't get on, that was a good thing). My sister drove all the way from Portsmouth and back in a single day - and we lived in Suffolk at the time so we're talking c. 400 mile round trip, simply not to miss the event, which I really appreciated.
I had a small wedding, family only (but as my family is enormous, it was c. 40 people). No fancy stuff, we actually had a Christmas dinner in the local Caffe Uno, because it was Xmas party season, there was 20% off if you ordered from the Xmas menu, so I just told my guests the Xmas menu was all that was available
If I were you, I would scrap the expensive place and just have a knees-up that everyone could come to. But that's me - this is your wedding and it has to be the way you want it. I would explain to people that they are welcome to come to the church but you've had to keep numbers for the formal sit-down bit very limited because of cost. Maybe offer to arrange for a table for anyone who wants to to have a sit-down meal together at the nearest semi-decent but not too cheapo place (at their expense) - and join you for the evening do?
I don't go to weddings where I'm invited for the evening only, they tend not to be local in my case.
I think you need to decide what is most important to you. If it's seeing the people you care about, you might need to sacrifice the posh place. If you want the fabulous posh place you might need to sacrifice some of the people. I don't mean that in a 'you are shallow' kind of way - I had to upset quite a number of friends by not inviting them to my wedding when they had invited me to theirs. Because I wanted a low-key do and was planning it fairly quickly (and dh was very unwell) I just had to make a rule of 'family only'. It's always a compromise, you just need to find the right one for you. And congratulations!