Just noticed this website with some interesting Brighton based races
http://brightonsports.co.uk/
The 10k starting in Woodingdean could be an option.
The Weakest Link looks like it might be fun too. I would have been right up for that Woodingdean 10K but I'm in France that day and will be running to and from the bakers for morning croissants to soak up the previous night's wine.