I feel your pain! I went through the same thing, even thought about doing one myself (for 85 people!) but was lucky and found a local woman who does them quite reasonably. I'm getting 3 tiers for 85+ people, well decorated, and a groom's cake all for £220
As far as what you can do.... well, if you're anywhere near Exmouth, I'd be happy to give you her number. But if not, M&S do wedding cakes, as do many of the supermarkets. I think you buy them in boxes already iced. No idea how good they are. You could also ask to have a couple cakes done at a bakery and just covered with plain icing and not tell them it's for a wedding. Decorate yourself with some simple fresh flowers. If it's 2 tiers, you can rent cake stands form someone else to keep the baker in the dark!
Hope this helps somewhat??!