Buy your wedding dress in the sales or 2nd hand - who's to know?
Does your local college have media students who could film it or photography students to take photo's?
Use a local floristry group (Women's Institute or a college or night class) for your flowers.
Taxi firms sometimes have a nice car rather than expensive Rollers, Vintage et al.
Consider marrying on a week day.
Print off your own invitations.
Use entertainers/musicians from local organisations - ask at your library if they have a database of Societies and Organisations or check your local 'What's On' pages for groups e.g. for Scottish dancing, Salsa, school bands, choirs etc
My 2nd wedding cost a fraction of my 1st and was a far better event through careful planning we had a fantastic day and a week's honeymoon everything paid for, all our family and friends, all the trimmings plus a few surprises for less than £5,000.
Very simple. Have an evening wedding. this way you only have to feed people once(on average 40% of the cost of a wedding is spent feeding people!) also its much easier to get away with a light meal. Think canapes and champagne rather than 4 courses! Why not incorporate a black tie and tiaras/cocktail dress code to get everyone in the mood.
Try and see if any friends/rels have a hidden skill e.g cake making.
Cut out the sit down meal by having a wedding later in the day. this also cuts out the need for seating plans and placecards. If you are settled in a home already, you could ask for people to bring something for the buffet and something to drink instead of presents
Try and get floral arrangements that can be moved from the ceremony to the reception. also try and use flowers that are in season, they will be cheaper and you may be surprised.
Look on the internet for your dress, there is something for everyone out there for your bridesmaids(and the bride) the high street has some great finds
Don't be afraid to negotiate on prices for the reception, esp if during the week.
Candles and balloons make great table decs and are cheaper than flowers.
Buy plain wedding cake from M&S and get your florist/youself/friend/relative to decortate. This will cost much less and will look great as it will fit into the day perfectly.
Some things just aren't important to us - the car, the cake, lots of flowers, expensive table decorations or favours - so we have just left them out, saved over £1000 already!! My mum made all the bridesmaids and pageboys outfits for about £200 altogether; we are getting married at 4pm, so only having an evening buffet instead of a sit down lunch. Because we have done it quite cheap, we can invite everyone we want to and also splash out on a lovely honeymoon...
Also, don't spend alot of money on things like invites and orders of service - I bought all my invites from WHSmiths for £20, and my mum and dad are printing out all the orders of service themselves; no one really remembers your wedding for what the invite or order of service looked like.