You are unlikely to be granted a .243W with a 'deer condition' if you haven't completed the DSC1 first, That is not the Law, but it is what most Police Forces require, as they can make up their own rules to a degree.
However, if you have a reasonable FEO he/she may be willing to support your request for a .243W variation if you provide evidence that you have booked a DSC1 course.
With a bit of luck, and assuming the process takes as long as it often does, you will qualify for the DSC1 and your new FAC with .243W will land in your letterbox in the same year.