The actress - who plays Whitney Dean in the BBC soap - was suspended without pay in July for repeated lateness.
The 20-year-old returned to work three weeks ago, apologising for her unprofessional behaviour.
She stated that she is aware of her "luck" in having a role in such a popular soap, and that she vows to improve her working life.
"Being suspended made me realise how lucky I am to be in such a loved show – I've really learned my lesson," she told the Daily Star.
"I'm just going to stay in from now on instead of going out all the time and I'm going to try to be good.
"I think I'll buy a big alarm clock with bells on so I'm never late again."
McGarty said that her co-star Patsy Palmer helped her get through her time away from the soap.
"It's like a massive family at EastEnders and everyone supports each other.
"Patsy is my biggest rock, she was really there for me and helped me through it."
The actress teased that her character Whitney will feature in some big plots in the near future.
"It's great being back because I've really enjoyed getting my teeth into some new storylines," she said.
"Whitney is a troubled character but she's got some happiness and naughtiness coming up."
Former EastEnders star Barbara Windsor recently criticised the lateness culture on the soap.