Found at Alice in the Internet
Dreamland by Alison Habens.
Published by Minerva, paperback published 1994.
"When the big night of Celia’s engagement party arrives, it happens to coincide with the plans of her hated housemates, each planning a party more outrageous than the other. Suddenly careening between future in-laws, radical feminists, and an Alice in Wonderland costume party, Celia veers off the path to married bliss, and along a trail of suspicious rapsberry tarts that leaders her into very strange places."