Is this the same as saying "I went to work?" That's accepted, but I'm a bit skeptical due to the difference in tense. Is there a different conjugation for something like that?
Yeah there's a bit of overlap in English, especially when you compare e.g. UK and US English. This is the perfect tense Dw i wedi "I have ...ed". You'll learn the simple past tense "I ...ed" a bit later on.
This is accurate in Welsh? There's no English translation that's grammatically correct?
Yes, the one given: