The Deer Stalking Certificate 2 is a vocational qualification, so there is no course to attend. What this means is that you collect evidence of your knowledge and ability in various deer management tasks. Hence the need for a witness to observe you.
There are a number of courses available from BASC, that could help you with the background knowledge necessary to support you getting the DSC2 award. Examples are: helping you with your shooting skills or perhaps carcass inspection and preparation.
You should only put yourself forward for assessment when you have reached the required level of knowledge and experience. This evidence must be 3 years or less to be considered as current evidence.