Recording purchases when not VAT registered

I am a Sole Trader and not VAT registered.

I purchase materials on behalf of customers from VAT registered companies.

When invoicing customers, I charge the customer the cost of the materials including the VAT paid.

I, therefore, assume that VAT is not reclaimable from HMRC.

Thus, when recording the purchases do I need to be recording the VAT paid?

Do I record VAT on stock assets? Do I record VAT on items such as stationery and fuel?

Hoping someone can unboggle my mind!