Tax on stock options

I'm posting this here because I can't seem to get an answer in the Taxation forum. Mods feel free to move it if you don't think it's the right forum.

I need some advice on the taxation of stock options.
When I started my current job part of the contract was a stock option grant of 1500 shares.
These were granted after my probation period finished but I never did anything with them. They started vesting after 12 months and are currently vesting on a monthly basis. As of last week 500 of the 1500 were exercisable. I sold my 500 exercisable shares last week.
I need to know how these are taxed. Is it CGT or are they taxed under income tax rates?
Can someone explain what I need to do? What forms need to be filled out? By when? etc?

Unfortunately stock options are treated as benefit in kind so you pay income tax on the difference between the grant price and the price on the day you exercise your vested options; you then pay CGT on anything above that if you held the shares and sell at a later date. I believe you are supposed to pay the tax within 30 days and if I remember rightly you need to file Form ROS Form 11 or RTSO1 something like that...

You need to return the RTSO1 form with payment within 30 days of when the options were exercised.