I have now had the opportunity to read the e-mail correspondence and give your concerns serious consideration. I have also spoken to the Headteacher at Parklands Girls High School.
I understand that you wish to follow a particular interpretation of Islam with regards to the covering of the face by females. You may be aware that a similar matter was the subject of a judicial ruling with regard to a female staff member in Dewsbury. In the Dewsbury case, the school's request that the full face is not covered was accepted by the law courts.
Ms. Lane has no objection to your daughters travelling to school with their faces fully covered, but requests that on arrival to school that they uncover their faces. I would support the decision of the school and would request you to comply. I understand that this is not the outcome you were hoping for, nevertheless it is the school's decision that needs to be upheld.