Depending on what distinction you make between land cover and land use, the Land Cover Map 2007 may be of interest to you. Released in 2011 it is, as far as I'm aware, the most up to date land cover dataset for the UK as a whole. There are several different versions: a 1km raster, a 25m raster and a vector dataset. The 1km raster uses a simplified ten-fold classification scheme and is free for commercial use; the other two use 23 land cover classes and are only free for academic purposes.
There are a number of older datasets in the same vein which may be useful if you're interested in changing land cover over time: LCM2000 and LCMGB1990.
One downside of these datasets is their lack of detail in agricultural areas, which are simply classified as either "arable" or "improved grassland". If you need to distinguish between different agricultural land uses then, depending on your organisation, you may be able to access the Integrated Administrative and Control System (IACS) dataset. This is maintained by central government and, unfortunately, it's usually not available unless you're undertaking government research. On the off-chance that this applies to you, it's definitely worth investigating.