They did indeed have dictionaries, and phrasebooks, of a kind. Ælfric of Eynsham's Colloquy is one pertinent extant example: written in the later tenth century to help novice monks and scribes to learn Latin, the Colloquy is presented much in the same way as a modern phrase-book or language textbook might be, as a series of conversations and dialogues with their translation written immediately beneath. What makes the Colloquy so fascinating is the depth and breadth of detail it goes into about everyday Anglo-Saxon society: imagined discussions are presented with hunters, farmers, fishermen, herdsmen, merchants, tanners, salters, lawyers and cooks. As well as their written Latin, the format suggests that novices were equally encouraged to practice their spoken Latin, most likely for its use in day-to-day religious office, but also potentially as a Lingua Franca for use overseas. A typical introductory dialogue from the Colloquy is presented thusly:

T: Interrogo uos cur tam diligenter discitis?

Ic ahsige eoþ forhƿi sƿa geornlice leorni ȝe?

[I ask you, why are you so keen to learn?]

S:Quia nolumus esse sicut bruta animalia que nihil sciunt nisi herbam et aquam.

Forþam ƿe nellaþ ƿesan sƿa stunte nytenu þa nan þinȝ ƿitaþ buton ȝærs 7 ƿæter.

[We do not want to be as wild beasts, who know of nothing but grass and water.]

The British Library in fact recently held an exhibition of artefacts from the 'Alfredian Renaissance' of the late ninth century which included the workbooks of trainee English monks from the period. Like the Colloquy, these workbooks contained a wide variety of Latin words and phrases with their (Old) English translations written underneath. You can read about that exhibition here.