I've fixed it. So in the interests of sharing I'm going to post the answer:
I was handling the redirects in the Dest portion of the config file when adding !in_addr I wasn't telling squidguard were to send the redirect so it just passed it through the correct thing to do is this:
acl {
IPS within nonworkhours {
pass whitelist !in-addr !adult !porn !hacking !phishing !spyware !virusinfected !dialers
redirect
http://somesite/some.html
}
else {
pass whitelist !in-addr !adult !ads !antispyware !artnudes !chat !dating !dialers !drugs !instantmessaging !kidstimewasting !onlinegames !phishing !ringtones !sexuality !spyware !virusinfected !weapons !webmail !porn !hacking !aggressive !violence !warez !mail !admin all
redirect
http://somesite/some.html
}
default {
pass !in-addr whitelist
redirect
http://somesite/some.html
}
}
That tells squidguard to redirect to a given site.
a very happy
Rat