Mate the best thign to do (And depnding how keen you are) is to create a proxy/firewall server (I use IPCop because its free and has VPN access allready (Open VPN)) with some cheap old computer with 2 network cards.
Its really easy to install and configure, there are heaps of tutorials on their website.
Also the next thing is, i am assuming you are using a ADSL connection at the work premises? If so then you simply create 2 interface connections throuigh IPCop, one being RED (Internet facing) the other GREEN (Internal network facing). You assign 2 ip networks RED gateway would be like 192.168.1.254, the ADSL LAN IP would be like 192.168.1.1, they are both on the same subnet.
The next thing is assign a new DHCP scope on the server (Or not as long as it isnt of the 192.168.1.0/24 network) and ipcop will route them 2 subnets.
The enxt thing is to create sopme SSL certificate through ipcop (very easy) add an account with a password, and when you get home you downlaod/install OpenVPN client, unzip the ssl cert you created and place in the folder (Its in the instructions) and then make the secure connection.
I might actually do a full screen by screen tutorial one day because we get this question all the time on this site and this is a great free alternative which doesnt make a direct connection to the server from the internet unless its authenticated.