Last month, show bosses announced that actress Michelle Hardwick had been cast as Vanessa, who is an old friend of Henry's alter ego Rhona Kirk.
Vanessa is a fun-loving character who will be taking up a position at the vets' practice next month, leading to clashes with Rhona's husband Paddy (Dominic Brunt).
Henry told Inside Soap: "Rhona was young, free and single the last time she and Vanessa were hanging out at university. We've just started filming the scenes where Vanessa returns to her life.
"They're great, because Rhona starts becoming more of a 'lad about town', as it were - while poor old Paddy is left at home literally holding the baby.
"I think there'll definitely be quite a few fireworks when Vanessa arrives!"
In the meantime, Rhona has another drama ahead next week when her new work colleague Brett Harrison, played by Gideon Turner, misreads her signals and makes a move on her.
Henry confessed that she was nervous about filming the upcoming scenes.
She laughed: "I get in such a state about things like that! I'm just terrified that I'm going to look like a complete idiot in some way. It's genuinely quite an unpleasant experience, as you've got a roomful of men standing about watching what's going on. There's nothing remotely romantic about it.
"Thankfully, Gideon was delightful. It was entirely my pleasure by the end - it could definitely have been a lot worse!"
Emmerdale airs weeknights at 7pm on ITV1, with an extra episode at 8pm on Thursdays.