Congratulations. If I remember correctly you are probably very shocked but very happy.
I've got 7 week old twin boys and I found being pregnant with twins pretty tough towards the end. You will probably get scanned every month or even every fortnight depending on the type of twins you are having. It's reassuring to see the scans but towards the end of the pregnancy it's very tiring going back and forth to the hospital. There are a few risks associated with twins that aren't associate with single babies, the main one being Twin To Twin Transfusion Syndrome but your doctor will tell you about that and what to look out for.
Other than that this, there isn't much difference between a single baby pregnancy and twins (apart from the weight gain)
If you work I would plan on stopping or stopping travelling to work if you can work from home by 30-31 weeks.
Wait as long as possible to buy maternity clothes. You might end up bigger than the average maternity ranges. Buy a few key maternity pieces like a long cardigan and stretchy pants. I got so big that maternity stuff was tight especially maternity jeans and I ended up wearing flary non maternity sun dresses from places like Primark and Peacocks with a long maternity cardigan over the top most of the time. Buy some good flip flops as your feet might balloon. I lived in Birkenstocks for 6 month. They were great.
Buy the cheapest no frills baby grows and buy loads of them if you don't want to be doing laundry every other day. Other people will buy you fancy cute stuff ;) Buy a hand full of premature baby grows as your twins will be small but not too many as they grow out of them very quickly.
I great tip is to start buying nappies every month or week from about 25 weeks and stockpile them. This will spread the cost as you will go through hundreds a month ? it?s crazy.
Mine are currently in moses baskets and will probably be until 3 mth I would guess and then they will probably share a crib. We bought 2 large cribs but it was obvious once we assembled one that they could share 1 so we haven't even bother assembling the other one yet. I got pretty much all my stuff from Amazon. They are really reasonable and deliver everything within a few days but Primark is also very good for cheap baby grows, booties, hats and blankets. Also second hand stuff is great as babies grow out of everything so quickly most second hand stuff from classifieds and ebay is not used much and buying two of everything brand new can get pricey.
Also line up as much help as you can for after the birth. It's a lot of hard work and it's exhausting. Nab everyone who offers help and consider hiring some help if you can afford it. If you can't afford it then try to put aside as much money as you can now to hire a night nurse once or twice a month just to give you a night's sleep when you are totally exhausted.
Finally, clear out as much junk from your house as you can. Having two of everything takes up a huge amount of space so clear some space if you don't want your house to turn in to an assault course of baby gear.
Try and get as much done sooner rather than later when you can do a little every day. From about 25 weeks you could be the size of a whale and very tired, it will then become stressful if you've left a lot until later and can barely walk.
Gosh I'm sure there's loads more but I'm guessing others will post some more handy stuff.
T x
PS: Have an epidural LOL