Thanks for the extra recommendations. I'm going to start with:
The Crusades (Wordsworth Military Library): Robert Payne
The Oxford Illustrated History of the Crusades: Jonathan Riley-Smith (Editor)
France in the Later Middle Ages 1200-1500 (Short Oxford History of France): David Potter (Editor)
France in the Central Middle Ages: 900-1200 (Short Oxford History of France): Marcus Bull (Editor)

I shall slowly read the more specialised and hard to get hold of books as well; I shall appreciate them more after a little general reading. Runciman's trilogy proved a little too costly for me to get now; it was a choice between that and the two French books, and the French books pipped it. I've added all the titles and authors recommended here to my nice 'books to read' list, quite close to the top. They will be the next lot of history books I pick up.

I'm still open to more recommendations if people have any; a frog can never have too many books, and I recently sold about 150 not very good ones, almost entirely fiction I have grown out of or didn't like much in the first place.