Do you wear sunscreen OP? That's your first port of call, to limit UV damage to your skin. Make sure it's not just a moisturiser or foundation 'with added SPF', because in order to get the stated SPF rating on the bottle you would need to slather on loads.
Honestly, I wouldn't do anything too drastic in advance of your wedding in case you have a bad reaction or something. Or maybe go to a reputable skin clinic and ask for a gentle peel or facial or something, but at least 2 or three weeks before your wedding day so any redness or peeling has gone away beforehand.
Longer term I would also recommend you get on some prescription skincare, like tretinoin. It's not available in the shops, you would have to get it from a subscription service, or from a dermatologist (expensive option), or I get it from an overseas online pharmacy.
It is a stronger version of over the counter retinol, and works by increasing collagen production in the skin, and increasing cellular turnover - both of which start to decline as we age.
I started using it a few years ago when I was about your age, as I started to notice my skin wasn't looking so fresh and dewy anymore. It's brilliant stuff, and I highly recommend it, however I wouldn't go near it or any retinol until after your wedding day, as the first few weeks/ months on a tretinoin can give some people irritation and peeling, so you don't want to have any big parties to go to for a while :-)
If you look up tretinoin on these boards your will find loads of good advice, I would recommend you do a bit of research first.
There's a few other ingredients which are quite good -
Vitamin C serum (with the active ingredient L-ascorbic acid) gives a nice brightening effect to the skin, and over time it can lessen hyperpigmentation. It's also an anti-oxidant that has protective benefits against UV damage.
AHAs/BHAs - these are hydroxy acids, which give an exfoliating effect when used on the skin, and removes some of the dead skin cells on the surface of the skin - but can be quite harsh so use sparingly. If you have oily or combination skin beta-hydroxy acid would be better.
I know it sounds like a lot, but if you do some research and find out what works, it doesn't have to be complicated. Also my advice is don't bother with expensive brands, you don't need to spend money on big brand names, instead spend your money on ingredients that work.
I have quite a basic skincare routine, takes 5 mins in the morning and evening. My skin is looking better than it was a few years ago.
Morning:
Cleanse with gentle cream cleanser (I have sensitive skin)
Vitamin C serum (I use Geek & Gorgeous)
Sunscreen (I use high SPF everyday because I wear tretinoin)
Moisturiser (I use cheap CeraVe from Boots)
Evening:
Cleanse
tretinoin
Moisturiser
Occasionally I use an exfoliant like AHA, but not very often as I have sensitive skin.
Sorry for the essay!