Haven't read Helle, but between Foster & Mitchell it seems like Mitchell would be the more appropriate of the two for your needs. It's a good pick for experiencing the story for the first time, and even though it's more a retelling than a translation it still falls very close to the original. Here's a comparison of both versions, taken from Gilgamesh's rejection of the goddess Ishtar in Tablet 6:

Foster translation

Which of your lovers [lasted] forever?
Come, I call you to account for your lovers:
He who had [jugs of cream] on his shoulders and [...] on his arm,
For Dumuzi, your girlhood lover,
You ordained year after year of weeping.
You fell in love with the brightly colored hoopoe bird,
Then you struck him and broke his wing.
In the woods he sits crying "My-wing!"
You fell in love with the lion, perfect in strength,
Then you dug for him ambush pits, seven times seven.

Mitchell version

"Which of your husbands did you love forever?
Which could satisfy your endless desires?
Let me remind you of how they suffered,
how each one came to a bitter end.
Remember what happened to that beautiful boy
Tammuz: you loved him when you were both young,
then you changed, you sent him to the underworld
and doomed him to be wailed for, year after year.
You loved the bright-speckled roller bird,
then you changed, you attacked him and broke his wings,
and he sits in the woods crying Ow-ee! Ow-ee!
You loved the lion, matchless in strength,
then you changed, you dug seven pits for him,
and when he fell, you left him to die.