Caramalt is a funny one. A very light crystal malt.....to my taste it is far sweeter than what you would expect of a crystal.
BTW, if anyone is having a hard time finding speciality British malts I would be happy to post some out to folk in the US, but I'm guessing that postage costs would be quite prohibitive and make the malt seem ridiculously expensive. Nevertheless, the offer is there
As for a substitute.....difficult to suggest one as it has a very particular taste.