Several posts have already been made - I have made more than one of them - that explain that to you. You have chosen to ignore them.
Let me set out the key points as I see them, again:
1. Equating the cross and the headscarf makes for a poor analogy. The cross is a common symbol of the religion, the headscarf is a deliberate statement of a personal, moral position. A better equivalent would be the crescent. For example, here is the crest of the Nottingham Islamia School, about which I recall absolutely no controversy whatsoever:
2. The school crest identifies, to some greater or lesser extent, the moral atmosphere, direction and aspirations of the school. It does not make a statement about the personal morality of the wearer. An item of religious attire, on the other hand, most certainly does suggest that the wearer subscribes to a particular ideology or doctrine. Although mainstream Islam generally agrees that all muslim women should cover up to some extent or other, muslim women themselves only do so if they personally agree and wish to identify with the teaching on modesty. On the other hand there is no teaching in Christianity that says you must wear certain symbols in order to properly show accord with any doctrine or expression of morality. Plenty of people do use Christian symbols, such as the cross or fish, as statements of belief, but this is far from universal and to try to claim it's in the same category as the headscarf is simply absurd.
3. If you see a nun walking down the high street in her traditional headscarf, I predict you would *assume* she was a nun under holy orders. If you see a woman in identifiably Islamic dress with her head covered, I predict you would *assume* she was a muslim who wished to honour her religion's teaching on female modesty.
On the other hand, the thrust of the row over Fiona Bruce's crucifix necklace the other week was that nobody outside of loony-liberal BBC management would assume she was actually making a statement of religion by wearing it during the 10 o'clock news. The cross, due to its status as an item of jewellery and the fact that nobody executes by crucifixion any more (nor knows what crucifixion is, in many cases) has lost a lot of its impact as a religious symbol. So, even when it is worn with specific religious intent, its meaning is likely to be lost on a significant proportion of people.