UK LAW
Please note that these are only my very limited findings... please don't rely solely on, and do please take independent legal advice if you are going to take matters further!
UK Police
It is not a criminal offense to wear a skirt down the high street, but you have to remember that not everyone is as liberal as you would like, and you do not want to antagonize any situation.
I have only been stopped by the police once in my car in "costume", on my way back from the Way Out Club (a transvestite club). I must have been pulled over because I saw the police car in my rear mirror, and at the thought of the horror of being stopped and having to explain myself, I must have looked very nervous (rabbit caught in the headlights scenario).
The police do have the right to stop check and breathalyze you if they have any cause for any suspicion (and quite rightly so, in these days of drinking and driving etc.). My experience of the way they handled the whole situation was good. I explained how embarrassed I must look and the policeman reassured me that I had done nothing wrong, and committed no offense in the way I looked, and they respected my wish to stay in the car whilst they checked out my car details and breathalyzed me, then I was on my way home. I would love to hear what they honestly said down the station
There are guidelines for police behavior... see http://www.northernconcord.org.uk/Police-Policy.htm
And also see an interesting article from a police woman's honest opinion and after all they are only human police and transvestite guide http://www.northernconcord.org.uk/Police-Sense.htm
Employment Law
You cannot be sacked on the grounds of your sex, or sexual preferences.
On 30 April 1996 the European Court of Justice ruled in the case of P v S and Cornwall County Council that the dismissal from her job of a transsexual woman, because she proposed to undergo medical treatment for her condition, constituted discrimination under the terms of the European Equal Treatment Directive. The Court found that it was not legal to discriminate against a person on the grounds of their having undergone, or intending to undergo, gender reassignment.
Employment law is quite complex, so please see http://www.pfc.org.uk/employ/empguide.htm for further details, or contact a good employment lawyer.