Whoovian - for a bit of perspective, I live in a Northern ex-mining village. Our income is probably on the high side for the village, since DH is an IT professional. Up here, that simply means he earns above the national average income. To put it in perspective, only 280 families in our area of Co Durham have lost their child benefits, today.
Even in areas like this, there are some people who are "aspirational" in their buying choices, though. There are people who aspire to the posh and becks lifestyle as they perceive it, with "designer" clothes and just the right phones. So many people have Audis and BMWs and even though there are a lot of battered, dirty old 4WDs that belong to people who really do drive on muddy bits, there's plenty of smart ones, just a few years old, that belong to people in the same terraces that we live in. Next door had a lovely extension built onto their house, which increased it to over 1000sq ft, funded by a remortgage. A year later next door but one (Audi owning types, formerly into burberry check, latterly into small dogs in knock off designer handbags) got exactly the same one built by the same builders. Their garage had to be taller though (Idiots - they got the roof made so steep that it leaks). And they ran out of money and didn't finish it for a year.
I suspect that you do feel rather bulldozed by the school issue and what it's costing you, but you need to be aware that, if you are prone to the effects of peer pressure, you will feel it in any walk of life. I'm sure even the shallowest wives of the wealthiest footballers feel inadequate about the size of their bling compared to others.
And while people around you might have the bigger house, others might have more holidays, others might dine out more, I doubt if any with comparable income AND school fees can do all of that. The ones with more holidays might live off Sainsburys basics fake weetabix, Richmond sausages and pot noodles. The ones who dine out might only take the kids to the library to occupy them at weekends. You, however, are seeing a sample of what lots of families do and lumping all of those together. And it makes you feel like crap.
And you've not reacted to any suggestions, but I'm wondering whether you really do feel equal in your marriage. I might be getting the wrong end of the stick, but your DH's hang ups and priorities seem to be trumping yours. That's probably why you don't feel comfortable and secure.