Definately dont send her in good clothes! i know with my daycare they get really annoyed bcos they always send out letters stating "old clothes only" but parents still send them in very expensive flash clothes and then moan when they have paint etc on them!
Try TM for cheap daycare clothes, have a look in the bulk lots on there.
For her bag - just pack a few changes of clothes and medication, formula, dummies bottles etc. When my boy was younger (Astin) i would send him with 3-4 changes of clothes, nappies, his bottle, his dummy, his special alergy formula and his asthma inhaler.
Hope that helps