Wow, got to love the amount of people who don't have a clue what they are talking about.
As some have said, it is taxable.
Option 1, paid through wages, so tax deducted at source.
Options 2 & 3 - a Benefit In Kind, which your employer will pay NI on, and you will be liable to tax on. Your employer will declare the value on form P11D, which will be given to you at the end of the tax year. It will also be sent to HMRC.
When they receive the P11D, and the P14 declaring your earnings for the year they will perform a reconciliation, and issue you with any repayment you may be due, or issue a calculation showing how much you owe them, which will then be collected through the following years tax code, so during 2012-13.
The benefit in kind will not go into your tax code directly. HMRC will not know about it until the end of the year, and as a one off, it won;t be carried forward into the next year. Benefits In Kind (and other employment benefits) will only be included as such in the code for the year in which the benefit arises.
I personally would go for option 3, or possibly 2.