Try not to worry @Nowanextraone . No-one really knows what's going to happen.
-Labour might not get in (they've lost despite high poll leads before)
-Even if they do, they might change their mind on the policy
-They will probably try to exclude special schools. It will depend on the exact legislation they write (which they haven't said yet) but may depend on eg the nature of your DD's school and/or whether she has an EHCP plan
What you can do:
1.If your MP is Labour, write to them. Explain your situation and the impact this would have on you. Ask them to raise your case in the debate and vote against the change. Ask whether there's anything else they can do to help you.
2.Ask your school about bursaries, or else a payment plan where the fees are stretched over a longer period (ie after she has left school). Unfortunately, in a special school there may be quite a few families in your position, but the school will try to help your DD to stay
3.Consider whether there's any way you could make it work. BUT first, weigh this up carefully against her continuing care needs: this might not be the best way to spend your money.
Eg. how much longer does your DD have in education? And sorry to ask bluntly, but is her education going to make the difference which allows her adult independence and even a job? Or will she need a high level of continuing care in adulthood?
I'd normally think it's a bad idea to do things like extend mortgage or take on debt to fund private education, but if you think it will make an enormous difference to her life outcome, you could consider it.
Wishing you and your DD all the best.