After doing a lot of musical theatre, and appearing in Grease, Les Miserables, Cats and a few other West End shows, I stepped back to be with my two children and concentrate on teaching. I have been at Tring Park School for the Performing Arts in Hertfordshire for four years. I teach GCSE drama and four BTEC modules: improvisation, devised, physical theatre and musical theatre.

I got a call from the Mamma Mia! guys, saying that they needed someone to be Meryl Streep’s body double in the film for the shots where you don’t see her face. Luckily for me, I had played the part of Donna before, as well as those of her two friends. They needed someone who knew the steps and could sing the songs.

I rang the casting director back and said: “What does this mean? Am I working with her or am I cutting her toenails?” But inside I was thinking, “Oh my God, that would be absolutely incredible”. I really admire Julie Walters as well - she is a national treasure - and jumped at the chance of working with her.

When I first met Meryl, I thought she was absolutely stunning. She doesn’t look her age at all, and her skin is flawless. We were filming at Pinewood Studios in Buckinghamshire for about six months and she exceeded my expectations. She will do a scene about eight different ways. She would do it the first time and you would think, “That’s amazing”. Then she would look at the screen and want to do it again. I learnt a lot from watching her.

The crew then moved to Greece, and I was there for about a month at the same time as Meryl. It was gorgeous. There were times when we were shooting a scene on a cliff edge and you would pinch yourself and think, “I can’t believe this is work”.

I remember the first time I met Pierce Brosnan, Colin Firth and Stellan Skarsgard. I had slight butterflies, but I wasn’t nervous. Some of the younger dancers were a bit in awe, especially around Colin, as they all fancied him.

The choreographer, some other stand-ins and I taught them the Greek step - the dance to Voulez-Vous. I had Mr Darcy on one arm and James Bond on the other, and just thought to myself, “This isn’t a bad day at the office”. I think the two of them were actually a bit nervous because they weren’t in their comfort zones.

There was a real sense of camaraderie in Greece. The first day I was there, Judy Craymer (the producer) threw a big party and Meryl and the gang were singing karaoke. Meryl was relaxed and would just hang out with the team. She wasn’t being the big movie star at all and we would all have meals together some evenings.

I had to stop school for about eight or nine months during the filming, and luckily the school was kind enough to let me do that. When I came back to school, everyone wanted to know all about it. I have to say I spent the first week back just recounting tales and showing them photos.

I have been back doing Mamma Mia! on stage in London again, so I have been teaching in the morning and doing the show at night. The film was successful because it crosses generations. It appeals to everyone, and it has been a massive boost to the stage version.

Being in the show has made a huge difference to my pupils. A lot of them have come to see it and I think it makes them realise that it is an attainable dream. Having a performing career is not from another world - it is about me coming into school in the morning looking shabby and worn- out. I think the experience has also helped me as a teacher. Now that they have seen me in action, my pupils have more trust in me. They know that I know what I’m talking about.

Sara West was talking to Meabh Ritchie. If you have an experience to share, email features@tes.co.uk.