After looking on the O2 website. Calling abroad from the UK (to Europe) is 89p/minute.
However if you text it uses 4 standard (free) texts for one text abroad. So it might be cheaper

---------- Post added at 22:06 ---------- Previous post was at 22:05 ----------
If he's on business... won't the company get his expenses? If so get him to call you as Zing said