Hannah and her bandmates - Paul Cattermole, Jon Lee, Bradley McIntosh, Rachel Stevens, Tina Barrett and Jo O'Meara - first reunited in November last year to perform a special medley for Children In Need.
Then, some days later, S Club 7 excited fans even more by announcing an arena reunion tour kicking off in May.
Speaking on ITV's Lorraine today (10 March) about the band's first tour in more than a decade, Hannah said: "It's taken a while for us because getting seven diaries together has been quite a feat.
"And also I think we've wanted to wait a while as well because now it's quite cool and vintage because it was so long ago. It's lovely to come back."
The band will regroup next week for rehearsals ahead of the tour in just under two months.
Former Primeval actress Hannah added: "We start rehearsing next week so that's all very exciting. I'm looking forward to going down memory lane."
S Club 7 formed in 1998 and rose to fame by starring in their own hugely popular BBC television series Miami 7. The pop group achieved four number one hits with songs including 'Reach' and 'Bring It All Back'.
S Club 7 split in 2003 following Paul's exit from the band in 2002 - but after a 12-year hiatus, S Club are now back!
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Watch S Club 7's Greatest Hits Medley on BBC Children In Need 2014: