Rach there is a child in DS1's class who has a full time TA just for him and to support him in school, he is statemented (I am not sure exactly what for) he is in class with them and plays with them at breaktimes, eats with them at lunchtime he just has support just for him throughout the day. At lunch there is a person to cover his TA and they are there to support him with whatever he needs.
He is one of the most popular children in the class purely because the children see him as "X" to them X is their friend who likes shapes (obessively likes shapes) he is prone to meltdowns but they accept him and the meltdowns and don't stigmatise him for it as to them it is just how X has always been. There is a little girl with a lazy eye, she sometimes wears a patch but the kids don't even notice. Whereas to an adult we notice ginger hair, skin colour, glasses, mismatched clothing etc a child of 4/5 doesn't know to do this unless they learn the behaviour from someone else, bullies are rarely born that way they learn the behaviour from someone or somewhere.
Esther will have your support and love 100% and so long as she is happy in school she will learn and she will cope, your job is to ensure she has the support she needs to make her happy and then she will start to learn. I am sure you found with your son that the key thing is parental support - be it reading to them and with them, drawing and practising shapes and lines and later letters and numbers with then, you have to be there and behind her. It is my biggest bigbear at school when parents don't support their children in their schooling, she has you so she is already on a winning path
As for school meals the consensus amongst many of DS2s peers is that they will be having packed lunches as we aren't sure they would eat the meal options except on a friday when it is fish fingers! A friend of mine is a dinner lady at school and if you notify the school that your child is a slow eater or needs assistance with cutting up food or similar then they will go out of their way to help - there is even a slower eaters table at our school, DS1 isn't aware of it but staff and dinnerladies have confirmed it is there.
In terms of the school computers, I doubt they will be too complex or valuable, they are quite hardy and letting her join in will help her. So long as they know she is respecting them as much as she can they can accomodate and adjust their expectations and supervision accordingly. Have you got a meeting date with the school to discuss your worries before she starts? Maybe even before the traditional meet the teacher just a meet the school head/deputy head/senco to help you get your head around how best to work together to help Esther.