Hi Chocolatecookie
The market is saturated at the moment but that dosn't mean you could not succeed. You just need to make sure you differentiate yourself. The main threat (as mentioned by another poster) is the increase of cheap copies from China, this is mostly affecting the low to mid end sector of the market as most off the peg dresses are produced in China or America anyway. I don't know what your plans are but if you were to stock mi/high end designers the chinese copies will become much less of an issue, as if a bride has a higher budget she is much less likely to prioritise price over experience, and will not risk not being happy with the dress.
You will need to check with the designers you are interested in about their exclusivity clauses, these tend to be in the 20 - 25 mile range, but this is not so much of a problem as research shows a mid-high end bride would travel between 60-90 minutes to a dress shop that offered the right dress and experience, so you should be able to find somewhere that would work, the main thing is finding a premises and location that represents your brand, i.e if your going mid/high end probably not next to a kebab shop or Tesco! If your good at marketing, a secondary location would be fine also.
I read this quote from a trade report "you either need to go primark or prada in this climate", the polarised ends of the market are holding up, its the mid-range thats feeling the brunt.
Also, in response to another members post, if customers want the princess treatment, then give it to them! If other shops arn't providing that for customers in your area then thats your niche...regardless of whether a customer buys, every interaction you have in a walking talking marketing channel. Even if they don't find a dress they like, they will recommend you due to the experience they recieved.
Finally, the costs of running a bridal boutique are high, you need to look into ways of making the books work. Some of the highest costs come from rent/rates and sample stock so look into location, it dosn't need to be primary or have a high foot flow, and check which suppliers make you re-order once a year or twice a year and how many.
People will always get married but customer expectations change, just match up your offering to current expectations then you will be fine.