For those who are trying to get this work it's as Adrian said.
You first do the normal omnipay paypal payment and then afterwards:
- get the token you were given
- preform a second call to paypal using the call getexpresscheckoutdetails method
- this returns all the info you need
API info here: https://cms.paypal.com/uk/cgi-bin/?cmd=_render-content&content_ID=developer/e_howto_api_nvp_r_GetExpressCheckoutDetails
The php script paypal provide to do it all for you:
https://cms.paypal.com/cms_content/ES/es_ES/files/developer/nvp_ECGetExpressCheckout_php.txt