What happens if they get excluded?

What an astonishing lack of sympathy marriedinwhite. The OP is not disruptive, her child is. The OP is seeking advice and help and is probably all too keenly aware of the effect on the school as a whole. However, she too needs help.

I teach but don't have anything to offer except my sympathy and thoughts. Sometimes a fresh start can really help. We find poorly behaved children from primary often reinvent themselves when they arrive.

While you may be correct, marriedinwhiteisback, you are displaying astonishingly little empathy.

OP there are PRUs which are fantastic and there are those that aren't. One thing which really matters is the parent caring about the situation and working with the school to get the best possible way forward. Your dd is lucky to have someone taking her interests to heart ecen when her behaviour is bad. Best of luck to you.

I'm going to talk to you about this from the other side OP. Inasmuch as you are worried about your daughter - what about the other dc in her class and the impact on them maximising their potential; their enjoyment of school; their stress at wondering who is going to kick off in or disrupt the next lesson and spoil their days at school. What about the teacher's positive attention they don't get because so much time is spent on girls like your daughter.

There were about five or six girls like your daughter at our dd's small high performing state comprehensive. The school could do little about them permanently in spite of appalling behaviour. Our dd used to come home in tears sometimes and the days she had a double lesson with some of the brats first things would leave in tears.

Fortunately we had the means to move our daughter to the independent sector where unacceptable behaviour is dealt with immediately and there are no politically correct soothing meetings and psychobabble

Your daughter is raining on the parade of everyone else. Why shouldn't she be in a rough school - she acts rough and will fit in there. She will do less damage to other children's education.

I'm sorry OP but I have a little sympathy for you and absolutely none for your daughter. She needs a wake up call and it might be that a few weeks in a PRU provide it. There are probably ten local girls who are well behaved who bite off the head teacher's hand for an escape route from the rough school.

Things are obviously not going well.
However you do need to understand certain facts around exclusions. Firstly any internal exclusion is not an exclusion in terms of the discipline code. In effect many pupils are excluded permanently for what is termed persistent disruptive behaviour but to be able to do that the school needs to demonstrate that it has exhausted all avenues to improve behaviour. Part of that route does need to be short term exclusions and I think that you are lucky that the school is taking a relatively lenient view of the swearing at a teacher, that would definitely have been a short fixed term exclusion in my secondary school.
There are other acts of poor discipline that could mean permanent exclusion for a one off offence. So such things as fighting, hitting a member of staff, having a dangerous weapon on site or drugs are all acts that would justify a permanent exclusion for a one off offense.
I think that the other issue you need to try and address is the underlying reason for this poor behaviour. Is she struggling in class? Does she have special needs that have not been identified? Is there an issue at home? Think it is time for a serious word with daughter and with the school to establish exactly what is going on at school.
If the worst does happen, then the LA are ultimately responsible for finding another school for your daughter, but the first stop may well be a Pupil Referral Unit (PRU) to see if their specialist staff can ascertain the reasons for the poor behaviour. The chances of it being a "good" school will depend on the local circumstances but I would no hold your breath.

We have excluded for a long line of " low level" behaviours, although swearing at a teacher is serious and we would have excluded for at least a day. However whenever we have issued a permanent exclusion there has been a series of short exclusions starting at a day and building up.

My son had a managed move from one school to another because we were concerned about a permanent exclusion and then facing very limited choices .

How many days has she had?
That is often true about schools with spaces but if current school is not working a new start even somewhere 'rough' may still be better

Has she had any fixed term exclusions? It is very difficult to permanently exclude a child especially for low level behaviours (rather than one off very serious incidents) and normally you would expect an escalation of fixed term exclusions before this.
You should also be having meetings at the school if the situation is as bad as that. It would be worth you arranging one I think.
If it does get to that point then another school may well take her under the fair access protocol and a fresh start. This can be arranged without your dd being permanently excluded. If she was perm excluded then a place in a pru becomes more likely.