Heya bluebell…
you most definitely could try it out…perhaps designate a section of your polytunnel to grow those strawbs… and if it´s forecasted for frost… double/triple fleece or even bubble wrap it? I´m not a huge fan on growing plants in pots as the watering an be a real pain…although we do have some grapes and blueberry plants growing in huge pots on our patio too. goooood luck! 🙂