co-contractor delivery of goods

The rule for co-contractors applies to both services and goods associated with those services.
Simply invoice everything at 0% vAT, and don't forget to include the legal text on your invoice:

'Reverse charge. In the absence of a written objection within a term of one month from receipt of the invoice, the customer is deemed to acknowledge that he is a taxpayer required to submit periodic returns. If this condition is not met, the customer is liable for the payment of the tax due, interest and fines in respect of that condition.