Flyfish. There is no such thing as a cross country "qualifier" any more, that is a relic from the past.
The JAA consider PPL training establishments to be organisations that are professional enough to train people for the issue of a licence. Part of that training involves X-country flying which builds up to a solo 150 nm X-ctry flight. No school should send a student unless they have met adequate standards of general handling and navigation. If the school wishes to conduct check rides, progress checks, or whatever, they are free to do so, they may on the other hand do it less formally with the authorising instructor accepting responsibility.
The Skill Test is an independant check that you have achieved the necessary standard for licence issue and can only effectively be conducted once all of the training has been completed.