Any direct cost you pass on at exactly the same price as your cost to your customer, you can treat as a disbursment, this goes for non vat registered sub contract work too.
If you wish to make a profit, then this is just a labour charge extra, at the normal VAT amount, shown separately.

If you wish to combine the charges then the disbursment rules don't count & you have to charge VAT on the whole amount.

HTH
Regards
Steve