How about a few sets of Disney princess lego? I've picked up cinderella's, Ariels, Rapunzels & Elsa's castles for my dd and they look amazing.
https://www.argos.co.uk/webapp/wcs/stores/servlet/Search?s=Price%3A+High+-+Low&storeId=10151&catalogId=25051&langId=110&q=princess+lego&authToken=
Cinderella's castle probably has the most wow factor, there's a carriage to go with it too.
Or if you have a wii how about the sing along disney game with a microphone?
Asda have added a few new princess fancy dress designs recently
https://direct.asda.com/george/kids/fancy-dress/princesses/D25M4G1C12S1,default,sc.html#https://direct.asda.com/george/kids/fancy-dress/princesses/D25M4G1C12S1,default,sc.html