YANBU.
Henzilla Re "I've always (obviously) known friend2 has a 6mo so I'm not sure how it got to this point." Freind 2's baby is imaterial, yuo are bieng railroade in to a trp you cannot afford, which you ahve told them you cannot afford, you need to make it plain NOW> I am happy to help organise this trip but I cannot attend, as i said aty the beginining I cannot afford it.
Re "But it has and now it's clear that she won't be there of course overnight so I'm in charge of that part of it." WHY? Why are you in charge?
" I just want to cry." Go and tell your story to your FRIEND who is getting married. To be honest if she does not understand she is not a real friend. Your friend 2 with baby has not listened to you and you need to make it clear. I am happy to plan, I am happy to go out locally, I cannot attend, as I said at the start I cannot afford it.
Re "These are my friends and I love them and want bride to have a good time." YES but you are a person too, with feelings and needs, just because you are not getting married and don;t have a six month old baby, you are a person and you count. You said you could not afford to go. Just make sure they realise this means you will not be going.
Please explain to your friend that you are not able to attend. She is welcome to go ahead and have a big night out in London if she wishes and you could offer to host or organise a fun local night out if you want and if she wants.
It is not worth getting into debt to be able to celebrate with her and if she is a real friend she will understand.
I am afraid my hen night was pretty boring and generally the idea one has to go mad and let one's hair down before marriage, when you could already be living with the person anyway, is a totally outdated and silly idea IMHO!
Be honest with your friend.
You should not have been put in this position and the friend who tried to organise this and then stepped down was very wrong to put you in this situation.
No cash/new baby both good reasons not to do this.
Want to do it/can afford to do it both good reasons to go.
Be honest, this is a sign that you are not being listened to by your friends *and you do not deserve this."