Thanks, yet again.
I looked in httpd.conf and the only code I found that looked like it needed to be changed was:
I changed it to - ServerRoot "c:/wamp/www/" and restarted, but it wouldn't work (WAMP stayed in orange colour).
After a bit of messing around, I typed 'localhost/index.php' into the browser and it's showing the WAMP homepage. So I think I'm happy enough with that, it's all working, not exactly how I wanted it, but it's working.
Thanks for your help Steve.
Also in the httpd.conf file I saw these, looks like all other directories are pointing to c:/wamp/www/