I suffered from a similar sort of anxiety just after passing my PPL, the only way to get over this is to work through it, face your anxiety / fears and overcome them. Having an instructor / fellow pilot sitting next to you is all well and good but how long will this go on for? To pass your PPL, the candidate will have had to have flown at least 10 hours solo, he should just accept that he's done it before, he can do it again.....