"The cost to human lifes isnt quantifiable"
You and I may not think so however the treasury I suspect has other ideas. The cost of a permenant training detachment overseas precludes it as a viable option. In order to maintain an overseas det and carry out our commitment to the UK/NATO defence requirement we would have to purchase new aircraft, employ more people etc.... I suspect that despite the training benefits of flying abroad (or not) it will never happen as it is more cost effective to pay compensation to the British public for damage caused than to fund a permenant overseas det.
Incidentally I believe we have a reciprocal agreement with other NATO countries that allows them to Low Fly here if we do so in their country so that would rule that out.