Squid as local transparent proxy
I am trying to set up squid to make switching proxies easier. I have a laptop which I use at work and at home. At work, I need to connect to the internet via a authenticated proxy. At home, I connect directly to via mobile broadband. So I end up switching proxy settings twice daily, which is just irritating! To solve this I want to set up a system whereby I never have to worry about a proxy - my browser sees a direct internet connection which squid (on my computer) intercepts and forwards either to the mobile broadband connection or to the work proxy (along with the required authentication) depending on which is available. I've read various articles on how to do clever things with iptables and squid, but I don't understand enough of the networking jargon or concepts to know when I need to change to make it work in my situation, or if it is even possible.
Can anyone advise me on how to set this up?