The UK will struggle to meet the 5% biofuel obligation grown from its own land resources. The commonly held view is that it will need to import oil from Asia to process it into Biodiesel (at Teeside and other plants), import biodiesel directly (e.g. from the Americas) and import Ethanol from Brazil.

Biofuel yields are much better grown in tropical climates. And carbon offsetting will be greater, i.e. 90% CO2 emissions savings compared to 10-30% for domestic crops. In fact, people belive that there is more energy going into domestic biofuels that there is coming out.

Which leads to strong economic forces, such as cheaper imports from abroad undermining domestic fuels.

http://www.processengineering.co.uk/Articles/306506/Biodiesel+in+crisis.htm

There are better ways to use the land available and growing forestry crops for biomass heating is one of them.