Cotterill was appointed on Tuesday and faces a tough opening fixture as the Robins aim to manoeuvre their way past non-league opponents in a televised tie at the Lamb Ground.
A place in the third round and a potential clash against a Premier League side awaits the winners, but Cotterill insists his side must first focus on the task at hand.
"The FA Cup is a wonderful competition and we're looking forward to it," he told the club's official website.
"There are rewards (after the Tamworth game) if we can be professional and win. But the same rewards for Tamworth too.
"We have to be respectful but focus on us playing well. If we play well you'd hope we have enough quality to score some goals.
"They had a great result against Cheltenham in the last round, so that's why we have to be professional but humble. They're a full time outfit and will provide a tough test."