The usual go-to book for medieval Germany/HRE Is The Heart of Europe by Peter Wilson. It covers beyond the High medieval period and I personally don't like how it kinda bounces around the timeline but it's an excellent foundation.

A second general history is "The Flight & Fall of the Eagle: A history of Medieval Germany 800-1648" by John R. Sommerfeldt

There's also specifically "Frederick Barbarossa- the Prince and Myth" by John B. Freed. It's about Emperor Barbarossa but since he ruled for 40 years, it's a large snapshot of typical Imperial struggles.

So far I've personally found reading books about specific emperors and dynasties a better way into learning about medieval Germany since so much of medieval politics is about the personal power and charisma of the individual monarch and his networking.

I can't help with the Russian or English stuff, I'm an HRE man.

Anglo-German Relations in the Early Middle Ages

You can also check some recommendations in Are there any books on the German peoples, from Late Antiquity to the Ottonians? by /u/Libertat and mine (/u/sengaku).

If you are a total beginner of the topic (I'd rather suspect that you're not due to your finding of Horst Fuhrmann's classic), [Tinti 2021], focusing on the cultural relation, has just been published. Anglo-Phone studies on the conquest and the successive Christianization of the Saxon people has attracted much attention recently (see Rembold 2017 and Landon 2020 for the recent status of research), but the research on activity of Anglo-Saxon missionaries in the continent has mainly been dominated by German scholarship like Lutz von Padberg for long since the publication of the classic, Henry Mayr-Harting's The Coming Of Christianity To Anglo Saxon England (1st ed. 1977; 3rd ed., 1991).

Concerning the Anglophone scholarship in Early Medieval Germany, works of late Timothy Reuter ([Reuter 2013 (1991)] and [Reuter ed. 1999]) should be referred to at first. As for a bit older period, a series of the essays by Janet Nelson found in TRHS (especially its part I, [Nelson 2002]) also offer a convenient overview of the current consensus that supplemented the perspective initiated by the classic issued around the middle of the 20th century, Wilhelm Levison, England and the Continent in the Eighth Century.

Anglo-Rus connections up to 1066

I hope some of the cited books in my previous post, Anglo-Saxon Historians - Would the Godwin / Godwinson dynasty be able to call upon political support / military support coming from Denmark? might be interesting to you - two books on the Godwine family was published in the first decade in the 21th century ([Barlow 2002] and [Mason 2003]), and Walker's biography on Harold Godwineson also mention the fate of Gytha and other female members of the family after the Norman Conquest. It is also worth noting that the marriage bond between the ruler families between Rus' and Latin West in the 11th century is now the central focus on the research by Christian Raffensperger, the specialist on Kyivan Rus' (see below).

As for the possible political role of the female nobles (queens), I should also mention another classic: Pauline Stafford, Queen Emma and Queen Edith : Queenship and Women's Power in Eleventh-Century England, Oxford: Wiley Blackwell, 2001.

Medieval Rus' and its dynastic connection with Western Europe

Christian Raffensperger's Reimagining Europe: Kievan Rus’ in the Medieval World, 988–1146, Cambridge, MA: Harvard UP, 2012, would totally be written for the avid reader like you! The author also AMA'd recently in the following thread: I’m Dr. Christian Raffensperger, author of Reimagining Europe: Kievan Rus’ in the Medieval World, and I’m here to talk about medieval eastern Europe and, if you’re interested, the medieval factors in the war in Ukraine. AMA!

I also listed some more classics on the academic books on medieval Russia in:

• Books on medieval Russia
• any books on the novgorod republic?
• What are some good primary sources from Mongolian Russia (from around 1240 to 1400)?

Additional Works (mainly) Mentioned:

• (Histriographical Essay): Landon, Christopher. "Economic and military aspects of the Frankish conquest of Saxony." History Compass 19 (2021): e12643. https://doi.org/10.1111/hic3.12643
• Nelson, Janet L. “Presidential Address: England and the Continent in the Ninth Century: I, Ends and Beginnings.” Transactions of the Royal Historical Society 12 (2002): 1–21. http://www.jstor.org/stable/3679339.
• ________. “Presidential Address: England and the Continent in the Ninth Century: II, the Vikings and Others.” Transactions of the Royal Historical Society 13 (2003): 1–28. http://www.jstor.org/stable/3679244.
• ________. “Presidential Address: England and the Continent in the Ninth Century: III, Rights and Rituals.” Transactions of the Royal Historical Society 14 (2004): 1–24. http://www.jstor.org/stable/3679304.
• ________. “Presidential Address: England and the Continent in the Ninth Century: IV, Bodies and Minds.” Transactions of the Royal Historical Society 15 (2005): 1–27. http://www.jstor.org/stable/3679360.
• (Histriographical Essay): Rembold, Ingrid. "Quasi una gens: Saxony and the Frankish world, c. 772–888." History Compass 2017; 15:e12385. https://doi.org/10.1111/hic3.12385
• Reuter, Timothy. Germany in the Early Middle Ages c. 800–1056. London and New York: Routledge, 2013 [1991].
• Reuter, Timothy (ed.). The New Cambridge Medieval History, iii: c.900–c.1024. Cambridge: Cambridge UP, 1999. https://www.cambridge.org/gb/academic/subjects/history/european-history-450-1000/new-cambridge-medieval-history-volume-3?format=PB
• Tinti, Francesca. Europe and the Anglo-Saxons. Elements in England in the Early Medieval World. Cambridge: Cambridge University Press, 2021. doi:10.1017/9781108942898.