It is sadly against the law to have your front windows tinted, though from what I've seen its a lot down to the place where you take it to, to if they will do it or not.
I had all my windows tinted (Rear windows limo tint then fading out towards the front)
I was told to take the windscreen tint off at the place I work due to security reasons. But apart from that nothings been said by the plod.
Get it done, you'd be VERY unlucky to have to take it all off