I forward on my expenses [flights hotels etc] towards my EU clients at cost. How do I code these in QB so nil vat shows on invoice but vat still visible in QB?

There is no VAT to show, you should not be charging your EU customer VAT if you have their VAT number, your invoice is zero-rated.

The costs to you may have VAT in and you can claim those on the assumption you are VAT registered.

Flights are normally an exemply supply.

Be careful if you're are "flat rate" for VAT, you might find those expenses are costing you more than you think.