There are so many types of bra on the market now. Don't just think of bra's as straps or strapless, there's so many more options.
When thinking of wedding lingerie, don't think about what looks pretty, but think about what works under your dress.
For a low cut dress with straps this shape bra from Wonderbra is perfect. Just make sure if your dress is quite fine to go for nude rather than white so it doesn't glow through.
For a high cut dress, it might not look very glamorous, or what you'd planned, but this style bra from Freya will be perfect to show no lumps or bumps under your dress.
This strapless Wonderbra has been an absolute favourite of my customers for a few years now. It gives great support and shape, and I'd rate it over every other strapless bra I've seen.
A stick on bra is great for a backless dress, as long as the adhesive tabs don't show if it's a very open back. This stick on bra from Fashion Forms goes up to an E cup. You get what you pay for with a stick on, so it's worth investing in a decent one.
If you're happy going without a bra, but a little worried about nipples showing (it might be cold in that church!) then nipple covers are a great option. They don't give any support, but do mean you don't have to worry about pointy nipples under your dress.
Low back bra
This low back bra from The Cotswold Frock Shop is great for a fairly low back dress.
Low back bra extender
If you have a dress with straps that's fairly low, a low back bra extender is a very easy way to modify your regular bra. These are available just about anywhere that sells bras.
This 'Ultimate Plunge' bra from Wonderbra is absolutely perfect for a really plunging neckline. It gives great support whilst allowing you to wear a very low cut dress.
This bra has very low sides. I can't find one from a known brand, but I did find this one on EBay
If you're in the Bristol area, I can't recommend Perfect Fit in Keynsham enough, for quality bras and excellent service.
And if you really can't find a bra that works, but don't want to go without, there's the option of modifying a bra to work perfectly with your dress. I can help adapt a bra to work with your dress if you really are having no joy!