The Knights Hospitaller didn't become an official military order until the 11th century.
Not even then, they were not really militarised until the second quarter of the 12th century (though contrary to popular belief were given places to defend prior to the templars). Neither were 'confirmed' though until either the council of Troyes or a Papal Bull in 1149, depending on how you look at the religious power struggle.
Though the Knights of St John themselves were allegedly present in the Holy Land for roughly 500 years prior to the first crusade in 1096 but this is debatable, almost certainly they had some presence in Jerusalem for a 100 years preceding it as iirc one of the Norman Knights who would later go on the first crusade had made a pilgrimage some years prior to the 1st crusade.
Say 1988- I think by saying 'Simply France' he was meaning that the French spread their legal system when they were assimilating countries.
Scotland is an odd one, the Act of Union granted them the right to maintain their Church and legal system but their legal system is not that different to English.
It's tricky to answer your question simply, briefly the English legal system is essentially the soul of the country, it is what (among other things) the English civil law was about. Crucially perhaps, the big thinkers behind codification in the Enlightenment began their thinking when Britain was, relatively speaking, enjoying a massive period of stability. Those that wanted a code could gain no foothold as there was simply no reason to change nor did we get invaded by France.
Also i think you are confusing having a civil law code and codification, essentially a civil law code is the be all and end all for most civil law countries whilst codification merely implies the writing up of statute and in England, contrary to perhaps popular belief, is still quite absent. It is generally only in Criminal and Land law where much of the law has been put into statute and even then there are many avenues which are not.
Personally i wouldn't change the English legal system for anything and it is noticeable that out of the people that write up European Human Rights Acts originally the majority of them were English academics/lawyers, though i am quite sure others would have got there eventually.
The common law system advantages imo more than outweigh its disadvantages.