Apart from Latin, there would be the Anglo-Saxon language itself, which is a Germanic tongue and is indeed often known as Old English. It was originally written in a Runic script but by Alfreds' tme the Latin alphabet woiuld have been used. There are many extant manuscripts in the language, the earliest Anglo-Saxon literature dates from the 7th Century CE. As a point of interest, Anglo-Saxon poetry was based more upon alliteration than rhyme.
Britain, according to the archaeologists, had been an important centre of international trade since the Neolithic. By the time of Alfred wool, iron, timber and dyes were all exported, as were Welsh gold and Cornish tin. Much of this trade took place along the South coast, which was in Alfreds' kingdom, so between goods produced, goods imported and goods passing through, the kingdom was a wealthy one.