I keep an eye on future shows for another website, and in my experience the BBC rarely announce any broadcast schedules more than a month ahead. The commercial channels do publish lists a few months ahead so they can pull in advertising and sponsorship, but these advance lists are very changeable.
However, a site that does a good round-up of these things is
http://www.thecustard.tv - click on the "Coming Soon" section. It won't tell you exactly when things are going to start but it will give you a good idea of what's in the pipeline.