Children at wedding (for guests who are travelling)

Hello,
This is my first time posting and I'm in need of advice. After putting off planning our wedding (due to covid), my partner and I have decided to bite the bullet and have provisionally booked to get married next May (2022), so only about 7 months to plan (context: we've been together nearly 12 yrs, and engaged for 2yrs, so I have waited a loooong time for this). We're currently only planning to invite about 30 to the ceremony itself - immediate family and closest friends - and then about 75 more to the main meal and party. My partner and I have no kids and do not want any, and I find them super stressful to be around. Don't get me wrong, if someone has always wanted kids and is lucky enough to have them, then I'm happy for them, but I just don't enjoy spending time with kids. So I'd hoped to have an adult-only wedding in an ideal world, as I personally hate the idea of our wedding being like a children's party.

Unfortunately, lots of our friends and siblings have children....The sheer numbers would cost us a fortune if we invited all their children as well (there would be about 30 kids ranging from a few months, to about 7yo!) My future SIL has already said she's totally fine not bringing their kids as they want a day/night off, and most of our more local friends/family should all have the option of babysitters (6-7 months should be plenty of notice to arrange it), though I expect some cousins will moan if we don't invite their kids.
The problem is, I have a certain group of friends that I really want at the wedding, but they'd be traveling from all over Europe and USA, so I can appreciate that it might not be as easy for them to just leave their kids behind for several days, and some of them don't have family who can babysit for a whole weekend, and some couples will have babies that will still be at breastfeeding age. So for them the choice will be either a) one parent stays at home with kids and misses the wedding, b) they bring the kids with them, or c) they choose not to come at all. I also know that, as we haven't seen each other in ages (because of living in different countries and covid), many of this friendship group are looking forward to meeting each other's children for the first time.
In an ideal world, I'd hoped not to have any kids there at all (except for those who are breastfeeding - I'm not a total monster!), but feel like given the circumstances I can't reasonably expect these friends to come all this way without their children, especially if they're not invited to the ceremony itself either, (which I feel bad about, though they've all said they completely understand and are just happy to be invited).
I know I need to speak to wedding venue to establish at what age children will need their own seat and will start costing us money (we're paying for it all ourselves), but does anyone have any advice about a) handling other guests possibly kicking off about their kids not being invited if I make exceptions for guests travelling long distances, and b) if we do allow children, how I can minimise the cost and stress of having them at the wedding?
One friend (from the European contingent) has suggested a crèche so that parents can still have a dance, but I don't know if they genuinely meant a proper crèche with childminders in a separate room away from the party, and if so, if they'd expect us to pay for that, or if they just mean they would take it in turns to look after each others' kids at a table while the party is going on. I try to keep my dislike of children out of the WhatsApp chat, so I don't think they realise I was originally hoping not to have any kids there at all, so now I'm kind of afraid to broach the topic and risk saying something that might upset others, but equally I know it's our day and we should be able to enjoy it how we want.
Just not sure how to handle the issue without causing loads of drama!
Thanks very much in advance and apologies to anyone who is offended by my feelings on children! X