I can't give you an authoritative answer, but I'd imagine that the Thompson was retired because of being .45 calibre and Britain went with 9mm. Hence post-war you see lots of Stens and eventually the Sterling. The early Israeli army used Thompsons (and anything else it could get) along with 'Australian' uniforms and in some cases wide brimmed chindit-style hats (though the 'commando' sock hat was the most popular, followed by the beret).
If you're willing to do some conversion, then this is an option, as is adding Arab headdress and fielding them as Jordanians of the same period. The biggest problem I can see is the fact that nearly all the figures have Thompsons in the first place!