Help - what to wear for first interview in years!

[nervouswreck]

Have just found out that I have a job interview next Weds! All very exciting - but as I have spent quite a few years living in knackered old jeans, I'm now worrying about what to wear .... Can any of you S&B experts give me a hand, I wonder. It's a school office job - I'm size 8, 5 ft 6 and age 43 ....

would something like this [http://www.boden.co.uk/en-GB/Womens-Dresses/Above-Knee-Dresses/WH350/Womens-Flower-Burst-Shift.html?NavGroupID=4]] be too casual ... it is a bit £££ but wondered if it would be nice with a little cardi - or just not appropriate ...