Cant guarantee this but I also think that if you've got your C&G they will not accept it for your qual towards the cscs card unless you've been an indentured apprentice. Sorry if I'm wrong by the way but I'll try & check in the morning and get back to you.
See below for an email received.
To obtain a CSCS Card as a Plasterer you will need to complete the operatives Health & Safety Test and you will also need to hold a NVQ Qualification or have Apprenticeship Papers within the trade, if you have your indentured apprenticeship completion papers and your City & Guilds Certificates you will be able to apply for a plasterers CSCS Card, we do not accept City & Guilds Qualifications without evidence that an apprenticeship has also been completed.
If you do not have any the above mentioned qualifications but have around 3 - 5 years experience you can apply for an Experienced Worker CSCS Card. This card will be entitled to you for one year, this card is not renewable, and during this year one of our on-site assessors will come out on site and assess your work so you can achieve the relevant NVQ Qualification. Once you have achieved this qualification you will then be able to apply for the full 5 year skilled card with your NVQ Qualification that you have achieved.