Although you can encorporate a few halfs as a Marathon paced session.
for VLM2013 i did two warm up races and a few park runs. half marathon was end of january (marakech, but i am doing torremolinos this year at around the same time) and then the kingston breakfast run 3 weeks before. i incorporated the breakfast run into my training program - i was supposed to be running 20 miles that day, so did a 2 mile warm up, 16 mile race and then 2 mile warm down.
i was supposed to run these at marathon pace, but ended up doing them considerably quicker. while this wasn't the plan, it did give me a lot more confidence that my race pace was achievable, if that makes sense. i also did 3-4 park runs as well to stay sharp. i tried to run all of these races at an even pace, to improve my discipline for the marathon.
Cheers boys, not racing is going to be hard!