The picture shows a number of Britishisms.
“Fancy Dress” and “Mascot” are what this shop has on offer. It’s what we’d call in the states a cosume shop.
Also notice in the window it talks about “Hen & Stag Nites”. We’d call these “bachelorette and bachelor parties”. We’d also spell “nites” nights.
Don’t know what a school visit is.
Do like they say the shop is “the little yellow tardis on the hill”. I think the implication is it’s bigger on the inside.