This is just unbelievable. I mean, I believe you. That's not some weird code for Troll. I just mean...whoah.
So to get this straight:
BIL and SIL are getting married in Ireland. They asked you, living in Surrey, to give up on TTC after finally having seen a specialist, and after several miscarriages which they knew about, so that you would be able to go to the wedding.
Having refused to do so, they now expect you to fly, or drive FIFTEEN hours, with a four week old and after a CS, to attend a wedding where your DH will be expected to spend all his time with them and not you AND HIS NEWBORN BABY AND TWO YEAR OLD.
They've exposed you, knowingly, to a virus which might cause serious health issues in your unborn child, and have not apologised for this, nor enquired after the results of your blood test. Again, after several miscarriages.
They promised to put your PIL up while said PIL renovate their house, and then went back on their word and told PIL that you would do it. Without checking with you.
Your PIL are renovating their ENTIRE house, inside and out, in order to host a reception back in Surrey. And want you to host them, with said newborn and CS, in order to facilitate this.
They've chosen a schedule which specifically means that they need hosting exactly at the same time as your baby is due, and cannot stay elsewhere due to wanting to get to their clubs.
FIL expects to sit on the couch all day watching sports, and insisting on complete silence from your two year old.
They will only babysit, incidentally, if you pay for a Sky Sports package!
They believe that you should send your dog away in order to accommodate them.
Your DH has grown up always being the second best. His parents have expected him to put his brother first in everything, to the extent where he has absorbed this and believes that it is alright to expect his newly post-partum wife to host her in-laws for months (let's face it, it would be months) so that his brother can have a wedding reception - well, post-wedding party, really, isn't it? - in a totally renovated house. His brother's need to have two wedding celebrations trumps his wife's need to recover from an operation and bond with a newborn. Likewise, he seems to feel that it's appropriate to let his post-operative wife deal with a newborn and a two year old, in another country, for two days because his brother has dictated a set number of men-only events that he HAS to attend.
All I can say, OP, is thank goodness you're a strong person with clear boundaries and, I suspect, wonderful parents. Your DH should be thanking his lucky stars that he's with you, because you're the only thing that'll drag him out of this dynamic.