Julian, the 12.5 in Kirstey's note was £12.50 not 12.5% and is £10.64 landing fee + 17.5%
Hopefully last comment as this is a flying forum: yes you should add VAT to your invoice, but should not include the input tax you paid in the net you charge out, if you have reclaimed it. And if you don't reclaim it (for example if you don't have supporting VAT documentation), yes, the VAT man gets the VAT twice.
Regards
SlipSlider