You can download a modern English version of The Faerie Queene at Project Gutenberg at the link pasted below.
If you'll give yourself a chance, you might find that Middle English, which is what Spenser used, is really not that difficult to read. Spellings are different, especially in the use of vowels. Whereas today we use the spelling "fairy," Spenser used "faerie"; we use "knight," and Spenser used "knyghte." Most words should be recognizable to you, and those that aren't are probably annotated in the margin or in a footnote.
Middle English is the in-between form of English--between the Old English of the Anglo-Saxons and the Renaissance English of Shakespeare. It is heavily influenced by French because of the Norman Conquest.
I've pasted for you below a link to How to Read and Speak Middle English. Follow those 7 steps--and have fun!
The modern Penguin edition of the complete Faerie Queene is your best bet. It's in Middle English, but there are helpful notes in the back and a short glossary.
Honestly, the Faerie Queene is one of the most adventurous and bloodiest tales in our language, but the visceral power of it is only fully felt in Spenser's primal English. In fact, English then was far less tied to rigid grammatical regulation; and the spelling of the same word could be different based on how it was supposed to sound--or even when Spenser wants to make a pun (i.e., when drum becomes 'droome' to evoke doom). Only in the original is the Faerie Queene as terrifying and comic as it was meant to be. You will be rewarded for your effort, if only by way of an enriched imagination.