What miseryguts probably means is that your employer must honour the contract and pay you until the end of the 12 week period. This could either come about by one of three means: 1) you work normally but he doesn't want that 2) he pays you to sit at home - gardening leave. 3) he dismisses you soon and pays you the same money in lieu of notice.
If the third one is invoked, you would not be paid holiday accruals in the next 12 weeks. However any money paid in lieu of notice is treated differently by HMRC (I think) because it is not earnings - it is compensation because of a breach in the contract - and as such I'm pretty sure it is not taxable.