Success!!! I've just got back from Halfords and with a little help from Nathan Roach, The cog has been removed, threads on the hub are a little worse for wear in places (caused by myself with a hack saw), but nevertheless the cog is off and the threads are good enough to still be used. Now, I just need to obtain a cog, as I'l be building the wheels tonight, finishing the bike tomorrow and wanting to ride it.