There must be a wrong name in here - SMC Visa. When you apply under the Skilled Migrant Category (SMC), what you are applying for IS Residence, so I don't think you've got what you've said. Do you have a skilled job, and you were granted a temporary work visa because of that?
If you get within about eight weeks of the expiry of a work visa, then you need to contact INZ to ask them if it looks as though your Residence application might be dealt with in time, or do they think you should apply for a further work visa to keep you legal in the meantime. What usually happens is that, if someone's application has mostly been checked through, and it's just waiting on paperwork issues, officials will hurry it up, but if they're still hanging around for one or more replies from third parties to verify your qualifications and experience, they'll tell you to go for a further work visa.