I organised a full white wedding for over 200 people from all over the world in 16 weeks. It's not easy but it can be done:
Dress - ex samples, off the peg high street or (carefully) buying online all possible but ASAP in case it needs altered. You'd actually be timing it really well in terms of ex sample stock as boutiques will be clearing stock for new season samples for the high season. In fact I would recommend if possible you head to places this weekend (you may need to make appointments with the better boutiques but they also have the nicer dresses which also get marked down a LOT at this time of year. You could easily get a dress with a rrp of a few £1000 for just a few hundred. Also don't be afraid to haggle they're used to it, if they won't haggle on price try getting accessories thrown in)
Ditto bridesmaids dresses. You may have to compromise by eg having them all in same style but different colours or vice versa
Menswear - again entirely possible as long as you're flexible but get it sorted ASAP.
Cake - you don't need to use wedding bakers, a simple but elegant design can be made by any baker
Flowers - again simple requests can be fulfilled by any florist
Transport - be open minded and consider all options - there's actually some really fun ideas out there like vw campers or cartoon based ones - but get it booked ASAP. Or else just borrow a friends/relatives higher end car and decorate. Ribbon is easy to get.
Photographer - you have sorted.
Catering - if you stick to a party at home this can be achieved relatively easily, keep it simple and cover the main likes and don't go for anything niche. Meat, fish and veggie options, plenty of sides plenty of carbs. Red and white wine, something sparkling for toasts (most people really can't taste the difference between champagne and cava!), most commonly drunk spirits (vodka, gin, rum) and mixers, a decent lager for the beer drinkers would usually be adequate.
Entertainment - again if you're doing at home adding to a playlist while you're chilling of an evening (mners will be happy to make suggestions) that you can then play through good speakers will be enough.
Decorations - can I suggest Easter colours? Yellows and pale oranges then you will be able to snap up a load of cheap decorations next week. I did something similar.
Stationery - the only essential stationery is invites. These can easily and relatively cheaply be picked up in card shops, stationers and dept stores. Or print your own - plenty of templates online. If you wish get special pens to write them out with - silver/gold, calligraphy markers etc orders of service are not essential, the church can direct people to the right page in hymn books and most services are fairly easy to follow.
Email - the problem with that is a lot of people no longer check their emails regularly and older guests may not have email at all. Plus it is a nice little keepsake for guests.
It can be done. But you have to be super organised.
I would say start a hard copy folder for everything (to store contracts etc) and start if you haven't already a shared calendar with your fiancé so you both know when appointments are etc (my ex forgot to book a day off to get the licence/banns bit sorted and had to pull a sickie! If he hadn't we couldn't have kept the date)