You need to save on the hundreds of small things. My wedding cost roughly £8000 (I think, it was paid for by a variety of people). The more stuff you do yourself the more genuinely personal and memorable it will be and if you dont have two left hands it will look just as good.
Invitations - make them yourself and save hundreds. Use fancy card from the craft shop etc. It'll cost you the time of designing it and a few nights together in front of the telly sticking them together.
Favours, place cards and table decorations - the same, do it yourself. I spent the morning of my wedding blowing up balloons and decorating the reception venue with my brother whilst my wife got ready.
Luckily my wife didnt want a white dress and ended up in a red bridesmaid dress. This saved hundreds and was a bit of a talking point!
I didnae pay for everybodys kilt hire. Maybe this was very cheap of me.
Photographer. Loads of average photogs charge thousands and are average. Search around and find an up and coming chap and save a few bob and get great photos. (my brother for example http://www.jamesrobertsonphotography.co.uk/?p=45)
But if you choose wrong it will be big regret time!
There's loads more you can do - pick your own wine and pay a corkage and get decent value wine rather than expensive venue wine, we spent loads on the celeidh band and just had a cd of our favourite tracks to dance to after, it worked surprisingly well. Cake was modest, if you have a talented friend then you could save much money here. Most of the stuff you can do to save money is fun and you can do it with your partner.
Anyway, save on the small stuff. Pay the big money on the essentials. The essentials are clothes, venue, cars, food, music, photographer, the rest can be saved on.
Oh and i got married in a castle!