I could have written your post 3 weeks ago. I live in the US (moved here from the UK a few years ago), so probably not exactly the same, but I have tried to tackle this head on. Ds is 8 years old, in 3rd Grade, and is doing ok academically but really struggling with the disruption in class and I am worried he is going to fall behind too.
He is by no means the perfect kid - he struggles with his emotions and can lose his temper easily and unnecessarily - but he is very polite and kind and likes calm and order. He gets very upset with rule breakers and noisy environments.
I am capturing everything in writing - exchanging e-mails with the teacher, giving details on his anxiety and the changes I have seen in him, including disrupted sleep pattern and new strange fears, to ensure I have a record of what I have done and the teacher's actions. I also have been to sit down with her to discuss solutions - all very cordial and positive, but serious and pro-active, in case I need to go to head teacher to ask for follow up actions.
The teacher has set up a desk at the back of the class, in a calmer area, where he can go and work when things are too loud. He is allowed to get up and move there without having to ask for permission. I have also ensured he gets more time to finish work, as he is sometimes struggling with getting it done when things are too noisy. And I have underlined his need for more structure - so the teacher is making an effort to give him more guidelines in his work.
Finally, I have spoken to the school counselor, and she is keeping an eye on things and liaising closely with me and the teacher to support my son.
In exchange, I am working with my son on his temper - to demonstrate that I know it is a joint effort, not all down to the school - and I spend more time than I ever expected doing home work and ensuring he stays on track with his school work.
I am really hoping that the joint efforts will pay off - but if I do not feel comfortable in the next 1-2 months, I will be asking to meet with the head teacher for more action, possibly including closer supervision of the teacher and classroom.
Sorry - I did not mean to write such a long post, but maybe it will help you with ideas. Also, I find it is nice to know that you are not alone - even across the Atlantic.