Old English had sentences that ended in prepositions, similar to Modern English:
gað ge beforon; ic eow cume æfter.
Gregory the Great, Dialogues, Book 1
Old English also allowed the order preposition, object, verb:
Þis hé spræc on Iudea-lande: ðær wæs án eowd of ðam mannum þe on God belyfdon on ðam leodscipe.
This he spake in the land of Juda: there was a fold of men who believed in God in that nation.
The Homilies of the Anglo-Saxon Church by Ælfric, translated by Benjamin Thorpe
See also my answer here about believe in vs believe on. One commenter (KarlG) mentioned that this word order is "still strictly observed in modern German, a bit less strict in Dutch".
I don't think that English ever had "German separable verbs".
In particular, the following mentions both of the forms I outlined above, plus one where the preposition is stuck to the start of the verb, but it doesn't mention the form you're asking about:
Old English generally did not possess phrasal verbs as they are found in Present-Day English. They did exist, although they were rare. Much more common in Old English was the inseparable-prefix verb, a form in which the particle was attached to the beginning of the verb. These Old English prefixed verbs are directly comparable to current phrasal forms. For example, in Present-Day English, there is the monotransitive verb “to burn” and then the phrasal monotransitive “to burn up.” Old English had “bærnan” (to burn) and “forbærnan” (to burn up). The prefix “for-” remained affixed to the verb and could not move as modern particles can. Such Old English compound verbs were also highly idiomatic, in that the meaning of the compound form did not necessarily reflect the meaning of the root. Denison provides “berædan” as an example because it meant “to dispossess”, while its root verb, “rædan”, meant “to advise”. The phenomenon still survives today in the participle “forlorn”, as well as the verb “understandan”, which does not in Present-Day English mean “to stand underneath (something)”, but idiomatically “to comprehend”. Akimoto suggests that Old English prefixes often remained before the verb because Old English had strong object-before-verb (OV) tendencies, whereas Present-Day English is largely a VO language, which has made it possible for particles to travel to post-verbal positions. Some Old English verbs did function as modern phrasal verbs do.
The Historical Rise of the English Phrasal Verb