Your situation is not a big problem. what you can do is some thing like this : Join your computer to the office network domain. use a vpn to connect to it then use your account in the domain to connect your data shares.
At home, keep all home computers in same network. Whatever files you and people at your home want to use, may be shared at one place in a home server or any of your computer which has one common username password. Your computer can be connected to office and home simultaneously because workgroup only bothers about same IP network range.
You may also keep two different IP address in one network Lan card. More better if you use an extra network card one for internet and one for home network.