I've been sent a translation, of which is attached an 'attestation de conformite'. I've never had to deal with this before and am unsure what the procedure is. Should I translate the attestation, does it just need my signature left in the SL?
Yes, you will have to translate this document. It confirms that the product confirms to applicable EU directives. The signature states that the signer declares the conformity. The signer may be held liable. It's up to you but wouldn't sign it.