Hi,
Thanks, this worked well.
Though I had also tried using scripts and schedulers as explained here (http://forum.mikrotik.com/t/ip-web-proxy-allowing-sites-to-get-unblocked-for-certain-tim/52308/1) which also worked quite well. I prefer your option though.
I think the main difference with the two solutions is that yours allows me to disable or enable the entire proxy server, which is what I want, while the other one allows you to disable and enable specific rules on the proxy server.
Regards,
Femi