I think it's a good idea for immigrants to be taught english, especially now that the UK is in fact one big immigration hostel.
I don't think it's fair for people to be forced to learn english, thats their decision, what i do have a problem with is the government going 'right, ok, you don't speak english, lets change our country to make it more suitable for you to speak your own language. everyone else already speaks english, so we don't need to worry about them'
it's that kind of attitude that will inevitably cause more racial discord and general badness long term, because as said before, the parents may not know english, but woe betide if the kids don't either.