This is pretty straightforward.
The company's sales are its sales, leave them alone, credit notes have no role in this.
A simple way to treat this is:
1. The company is buying an asset and will need to get a VAT invoice from the other crowd. Dr. Asset, Dr. VAT, Cr. Creditors
2. The company now has a creditor for the full (gross) value of the asset purchase. This is partly cleared by an advance of funds from the director, (which I think is about 2.5k?), so Dr. Creditors (2.5k), Cr. Directors Loan (2.5k).
3. The balance of the purchase value is to be cleared by a contra of money owed by the other company (i.e. debtors) against money owed to that company for the asset (i.e. creditors). So the entry is Cr. Debtor, Dr. Creditor.
That accounts for the asset purchase, the VAT on it, and creates a loan balance owed by the company to the director. This money can be paid directly to the director at any point (CR. Bank / Dr. Directors Loan balance).