So, I've decided that 2013 should be the year in which I get a road bike. I'm not talking now, but in 3/4 months down the line. My reasoning for getting a road bike is partly for something to do in the long summer I get as a student (my last one coming up :O) which will let me stay fit and partly due to my long term want to do John O Groats to Lands End ride, which I'm hardly going to want to do on my Meta 5.
I'm new to the road world. What should I look for in a road bike? Any brands/specifics that should be avoided. I'll probably have about £500 to spend on the second hand market, for something in reasonable condition.
Also, what size would people recommend me to go and look at? I'm about 6'3".
Advice would be appreciated.