My ds can be very nervous and was reluctant in previous dressing up days. This year I have been talking about World Book Day quite in advance to get him excited and for the first time he picked up a character and was looking forward to going as that (Mr Penguin).
School have, however, decided to do a pj day instead! I just know he is not going to go in his pj-s, and neither would I to be honest, as they are just not the right clothes for the weather...
I'm sure most kids will still have fun, and they are probably doing because of COL.
Anyway, would enjoy reading what your little ones are going as and if you made or bought their costume. I do love all that.