I think as a mum your doing everything you can , you've figured out the stressors and have identified she's struggling. Lots of small conversations around it and being understanding will really help and redirecting of behaviour if your there to see it or you can use books and songs such as hands are not for hitting ect. 1:1 sounds much worse then it is, school have to have themselves covered and be seen to he putting things in place to support your little one. Sometimes it's 1 teacher and 1 TA in a class so by putting someone extra in it just means there's someone who can be more focused on your little girl and be there quicker to help her and redirect her before she becomes to frustrated and upset.
The 1:1 sessions will most likely be else sessions they're away from the classroom and play games and do activities to help them learn about emotional literacy (giving them words/tools to deal with things they find stressful). Lots of kids struggle in the transition to reception. It's a big change. School will have lots of strategies to help support your daughter.
My son really struggles with this, the school made him social stories about kind hands and we also got a book called hands are not for hitting. Also lots of reminders that if another child does something that annoys them to talk to a teacher. Also talking about thier emotions can help as often they don't understand thier emotions. Example: I understand your feeling angry/sad/ annoyed but it's not okay to do .... when we feel like that. My son still does hit out as he struggles with impulse control but doing the above does help.