Hiya, I am a qualified MUA and this is what I can think of -
Focus on good skin care now and work on making your skin as hydrated and as good condition as possible.
Also decide what sort of look you want - dewy and glowing, high glam, natural etc. Do you want sparkly eyes and highlight, or do you want a more subtle look? That will inform the products you use.
I would spend more on skin care and foundation, and lipstick. Less on blush, eyeshadow, brushes, etc. Make sure your brushes are clean before you use them for your big day - this can have a huge impact on makeup application!
Also, instead of just watching makeup tutorials on YouTube which can be overwhelming, consider the specific skills you want to learn - applying blush, or contouring, or a nice eyeshadow look etc. Be as specific as you can and you will find better videos.
Base will depend on your skin. You don't necessarily need primer but make sure you've moisturised with a good moisturiser (my favourite is L'embryolisse lait-cream). Foundation - if you have dry skin, if it's oily, if you have problem areas/acne.
I think its best to try out some foundations/tinted moisturisers in advance- everyone's skin is different and sometimes foundations can oxidise with your skin and turn orange! A good budget one is No7 whereas a higher end one I always recommend Charlotte Tilbury Magic Foundation.
Depending on whether you are oily or dry will depend on whether you set with powder - it makes your makeup last longer but can be ageing and make you look a bit dry if you have the wrong skin for it. Best powder I believe is the NYX HD powder - put it on after you've done your base, bronzer and blush (and highlight if you are doing that too). If you cant or dont want to use powder, a setting spray will help hold your makeup for a bit longer without drying you out as much. Urban Decay's is a 'cult' product although I do think the NYX one is just as good.
Blusher - consider your skin tone. To be honest my all time fave blush is the Nars one in 'Orgasm' but there will be more reasonable ones out there. My recommendation is to go to Boots, choose a counter such as No7 etc and ask them to recommend a blush for your skin. Then you can always choose a cheaper dupe in a similar shade if you can't stretch to a more expensive option.
Bronzer- I personally love Benefit Hoola and it is so natural and subtle. But there are cheap dupes available. Buy a kabuki brush and sweep across your face where the sun would hit it for a natural look (so across your nose, cheeks, forehead), or for a more glam contoured look, follow a '3' on either side of your face, in the hollows of your cheeks especially.
Eyeshadow - I would watch a tutorial for this - type in what sort of thing you are after, e.g. natural smokey eyeshadow tutorial etc. If you want something super easy, sometimes beginners find cream eyeshadows are easier to apply and can look quite striking - www.boots.com/maybelline-eyestudio-color-tattoo-24hr-cream-gel-eyeshadow I rate these for being long lasting and easy to use.
Eyebrows - I wouldn't do anything too dramatic. On the whole, most people suit their natural eyebrows. A bit of pencil to fill them in and shape them. If you have naturally thick eyebrows, get a good eyebrow wax and give them a brush. Make sure you clean any excess makeup from them!
Eyeliner - depending on your look, you may want to use eyeliner. But I would say this can be quite tricky if you're not used to it and can also be ageing. Maybe have a play around beforehand and see what suits you? NYX have a good selection of fairly priced eyeliner products.
Lashes - to be honest if you're not confident with false lashes, I wouldn't bother. So you could choose a mascara that suits you (again, everyone reacts different to mascara so try a few out - my favourite is the KatvonD one but it doesn't work for everyone!). The other alternative is to have lashes done professionally by a salon. You can get extensions that look natural or glam depending on what you want- also ones that last a few days that are a bit cheaper. If you're worried about them looking too OTT, a lash lift is a nice choice.
Lips - again it depends on the look you want. Think about whether you want a sheer, 'wet' glossier look, or a more matte, brighter look.
I personally prefer natural lips, especially as lip makeup can wear out quicker than the rest of your face so look obviously when you need retouching! I love the YSL oil based ones. There are also some lovely Chanel ones. Nars are good for the more vibrant colours. I think it's quite nice to have a special 'wedding' lipstick hence the more fancy branded ones. Every time you use it or see it, you will think of your wedding. But if you are on a tighter budget, perhaps try No7 or L'oreal or rimmel.
Sorry for the length of this message, I hope you find it helpful!!