Hello ladies.
Just wanted to say thanks so much for the advice you all gave me - have just read it through and think that everything that has been said is good advice. I also thought what a lovely and helpful bunch you all are!
TYG - you hit the nail on the head, I think. It's not an isolated incident of favouritism at all. MIL actively encourages situations where she can pit the children against us. Part of me (a paranoid part, perhaps) thinks that she likes to create situations where we will look the mean, nasty parents while she is the doting, spoiling grandma.
Anyway. DD is definitely not going anywhere at Easter as her exams are far more important. This was ruled out at the beginning and will remain the case. As for after her exams, I am sticking to my guns. DD is quite sensible and will listen if I explain the situation for her. She is also very close to DS and cares a lot for him. So, I think that I will speak to DD myself and explain why I've decided that she can't go (that it is not fair to treat any one member of the family differently from the others; that it may be upsetting for DS as he has not been asked to go nor would he be able to; that MIL has so far wanted nothing to do with the new baby and it will cause problems later on if she is selective about which of her grandchildren she is bothered with now; that I want to take the children to Ireland with DH myself). Obviously, DD will be disappointed but I think that she will understand. She especially wouldn't want her brother to feel hurt or left out.
LG&T - sounds like you're having a nightmare of a day. I so wish there was something I could do to help. With regard to the lump, I also think that you would have been sent straight off for tests etc if it even slightly looked like it might be serious. However, I know that it will be preying on your mind until you get it sorted. Seeing the midwife is a good idea, too - do you think that you might be able to book an appointment with her?
With regard to the school - what a let down! I would be tempted to contact the LEA and ask for their advice and assistance. It could be that maybe the LEA is strict about class sizes etc but if you contact them directly and explain the situation, they will be more understanding and accommodating. Ring up the LEA offices and get the name of someone you can contact (if not a person then at least a specific department).
Also, I hope that Phin's finger is ok. It could well be just bruising.