When I came to Canada last October, I was truthful with them, which was a good thing as they could see from my file that I had an application in process, dont lie, just say that he has come to visit you for a while, while the application is going through, make sure he has proof of the conformation of the sponsoship approval, and anything else that can show you have paid for the medicals ect.
I was given a year vistor visa, but got my PR 2 weeks after I landed, she told me that she was giving me a year to make sure that I didnt have to exstend my visitor visa after 6 months. What I would recommend though is that you do have a return ticket and that you have some proof of ties to the UK for your husband, such as a rental agreement or family or a job. Im saying this as they will also want to make sure that if the application was denied, that your husband will return to the UK.