To not want to do the following things at my wedding?

I just had to comment to say your dress is absolutely stunning OP!! Soooo beautiful.

I'm glad you are going to put your foot down. Definitely utilise your assertive people to advocate for you on the day as well.

Your dress is gorgeous.

This

Just have a quiet registry office wedding with only your grandparents in attendance.

Yep. Just about to say the same thing. I’d be off out of the window and down the ladder before you could say ‘Gretna Green’. The second other people try to make your special day all about them, it’s game over.

If your dad is saying he won’t come if his wife can’t drink, let them both stay home. There’s no reason they have to be there. Tradition goes out of the window when you’ve been raised in a non-traditional way. You said it’s not as simple as that, but it is. If they fall out with you over it, then so what? It doesn’t sound like they’re a supportive presence in your life anyway.

My family and DH’s are dysfunctional/abusive and we invited the very few people we wanted there. Nobody walked me down the aisle, my DH and I walked in together. No speeches, no bridesmaids. Just do it how you want and have what’s important to you (both).

Tell your parents only your grandad is walking you down the aisle. He's special to you, not getting any younger, and you want him to have this moment.
Don't bother with speeches. Groom thanks everyone for coming, best man does a toast, then straight in to dancing. People will be relieved.
Get someone to pack up a few sandwiches for his nan and take them over to her. She will feel singled out and special.
Tell your dad that if his wife kicks off she will be thrown out.
Tell your SiL your bridesmaids are your sisters and cousin only. You cant make exceptions or other friends will be hurt.
Whatever they say, ignore. Because it's not you, it's them.

Mathsbabe
"Why not move the church date forward and take your grandparents and someone who is important to the groom. Get married as you want. Go and have a lovely quiet meal or whatever you want.
Then use the venue for a party on the original day."

I do think that is an interesting idea. But if that isn't what you want then so be it.

Can I recommend you watch the wedding of Jom Halpert and Pam Beasley on The Office USA. It's so brilliant. It's a two-parter but the second episode is key. It's a comedy but it's very moving!

Vegas

1 - Tell her no and warn the venue.

2 - Tell her no and say 'because you might not be around in future and that would be awkward in the photos' then flick her the v's.

3 - Have Grandad, tell your Mum to button it or she's not coming. (Which solves 1 absolutely.)

4 - Uninvite Dads Wife and therefore Dad which fixes part of 3 and 1.

5 - ask annoying Nan what sandwich/soup/snack combo she will eat, supply that, do NOT tell anyone else.

6 - be firm on this and make sure some of your 'wedding team' are prepared to firmly eject children (and their accompanying adults).

7 - elope, but take grandparents with. You don't have to elope to the Seychelles.

I’m in! We ride at dawn!

Cancel everything. Take your grandparents, 2 best friends and cousin and whomever your fiancé is closest to, have a very quiet ceremony, then go to a restaurant. It will be relaxing and lovely.

I’m getting married and I am currently having the following issues:

1. My mother wants to do a speech at the wedding. When I say no she gets very affronted and says it isn’t fair my dad gets to do one (they are divorced and always acting like this). I’m honestly worried she’s going to tell the venue she’s doing one as a ‘surprise’. If she did do one it would be all about her and how wonderful she is.

you tell her it’s your day and she is t doing a speech. And if she does she will be stopped and asked to leave, this is not about her or your father. I would prewarn the event that she is not be stopped if she gets up to do a speech

1. My future SIL wants to be a bridesmaid and I don’t want her to be. I want my two best friends and my cousin (who is like my sister) to be my bridesmaids. SIL is very argumentative and keeps asking about it and isn’t really getting my hints. If it makes any difference I wasn’t allowed to be a bridesmaid at her wedding last year as “I might not be around in the future so it would be awkward if i was in all the pictures”.

1. i would like my grandad to walk me down the aisle. He is my best friend and practically raised me (along with my other grandparents). My mother is affronted I don’t want her when she’s “been so much better than my dad” and my dad is offended that I don’t want him even though he barely knows me. I’m tempted to have dad and grandad but I don’t really want to.

1. My dad’s wife is an alcoholic and has refused to not have a drink that day. My dad says if she can’t go then he won’t go. If she attends and drinks then she will cause a major kick off.

1. my fiancés nan is being extremely fussy over the menu. We’re having a pizza van to try and please all fussy eaters etc and she won’t eat “foreign food” so is kicking off that she’ll be hungry all day. (Kind of unrelated but at SILs wedding she only served food I was allergic to so I ordered a takeaway and ate outside! At no point did I even mention this at the time as it wasn’t my day)

1. we would like a child free wedding as we both had to raise our own siblings (who are now adults). We’d like an opportunity to let our hair down and have a fun party with other adults without worrying we’ll trip over a child! Fiancés family have said this isn’t fair to their 4-8 yr olds as they “love a party”

Go child free if that’s what you want. Tell them exactly why as you have stated her, but that you understand if they can’t get childcare they won’t be able to come

Stop beating your self up, stick to your plans and those that don’t like it don’t need to attend

Elope with your grandparents?

Yes but if you want grandad to walk you up the aisle, you don't really care that much about tradition.

Be fair.

If your mum raised you on her own, why shouldn't she get to make a speech in preference to your shitty dad?

I wouldn't have either of them giving speeches, if you don't want her giving one.

I know a couple that didn’t tell anyone and just went off to the Channel Islands and got married. It looked so light, fun and romantic. Just the two of them done their way. Then they stayed for a little holiday. Thats what I would do if I were you.

Some random thoughts:

Your dress is utterly gorgeous, makes me want to get married all over again!

I reckon a lot about how a wedding goes is in the attitude. If you go in expecting everything to be perfect and like something in a film, you're almost certain to be disappointed. If you and your fiance decide you will be happy to be getting married whatever happens, and prepare to treat any drunken shenanigans or whatever as a private joke as far as possible, you can't go too far wrong. We got married on a boiling hot day and at one point DH started feeling a bit sick, so we sneaked off to sit in the garden and cool off for a bit, and he said that was actually really nice cos we got a bit of private time (he felt better after some fresh air luckily!). There were various other minor hiccups too, but they all became stories to look back on.

For his nan, can someone do her a little pack-up of her favourite picnic-style foods to have instead of pizza, so it's like a little treat? As for the speeches and walking down the aisle, you don't have to stick to tradition and in some ways, the more off-piste you go, the easier it is (you can just laugh it off as wanting to do something "a bit crazy"!), compared to doing something nearly traditional but not quite, that might put someone's nose out of joint. So maybe your fiance could ask SIL to be an usher/groomswoman for him (in a dress if she wants!) instead, or some other role? And have completely non-traditional speeches so nobody feels it should have been them - which it sounds like you're already thinking of. (We did that to an extent, in part because my dad really didn't want to do one). A minder or two for your stepmum (and firm promise she'll be sent home at the first sign of trouble), and hopefully you'll be fine. Get a bit creative if necessary, but do what YOU want!

That sounds like a great idea - I always think it must be awful to have to worry about speeches so if those three want to do one, and you want them to, it sounds perfect!

is the venue providing a host / compere (sorry, not sure about the right term). Might help if anyone else tries to speak. They can cut off the mike.

I just wanted to add, OP - you are being very reasonable. Dont get drawn into justifying your decisions - because you dont have to. So if SIL asks about being a bridesmaid, just say “No, im having X, Y and Z only”. And with the parents, just tell them “We are having a child-free wedding”. Just keep repeating - No is a complete sentence (particularly at your wedding).

The only one I might give some leeway is old nan and her fussy eating. Just because, depending on how old she is, I am more lenient with unreasonable oldies! This is assuming she is genuinely elderly (85+) and not 68 or something.

And dont let them get to you. Your parents (and SIL) sound very unworthy. You dont owe them anything.

We had a big traditional wedding in many ways but -

No speeches - day it’s not fair on the best man as he will feel pressured. Also who gets thanked and who doesn’t is a minefield.

No top tables - we were all on round tables of ten and ours had bridesmaids and best man and other half’s so no one split up

No receiving line - just no.

I did have my dad walk me down the aisle as we are close but just makeup something about it being anti feminist or hold firm on grandad

This.

Genuinely, hire a bouncer to be on standby for all these eventualities. Ask the coordinator for advice. Bet it's been done in that venue already, many times.

Do not cave to anything. This is the one day in your life where you get to decide on all of this stuff.

Cave now and forever hold your peace, for anything going forward where your families are involved.

Go with your grandparents as witnesses

I agree with @excelledyourself

"... knowing that it might be the very catalyst you need to free yourself of some human baggage.
See the wedding day as a fresh start, where those who love and respect you can choose to be a part of your new life or walk away from it if they can’t get over themselves."

Please see this a fresh start.

Based on your update re your mum (page 3) I would feel free to bar her too if she kicks off.

Have a quiet register office service with just your grandparents - you could do it before the expected wedding day. Then afterwards tell the rest of them and invite them to a party/meal/day out or whatever to celebrate, as long as no one can take over or make speeches.
I had a very tiny wedding because of family issues - and it was lovely - just the two us and three people who really care for us. It was the best thing ever for us.

I agree @chilibandit your wedding, your rules. Grandad walks you down the aisle and does a speech. Your choice of bridesmaid. SIL can put up or shut up. Mum and Dad - attend, no speech, tough if they don’t like it.

enjoy your day and I’d probably not have the veil ‘cos the dress is stunning 🥰