I'm a triplet mum and to answer some of your questions (from a UK perspective) and my boys are now 6 so things may have changed.
You will be very big. Depending on your job you may need to finish early (if you can l, get signed off by a doctor and don't take may leave early).
They mandated a c section and I was happy with this. The maximum they take you to is 35 weeks and I had mine at 34+1. I had scans every two weeks and they monitored me closely nearer the time. They do get more interested after viability at 24-26 weeks. You may go for a scan and they go right they're coming out tomorrow! They will offer you selective reduction early on but they have to as per nice guidelines. I couldn't have any prenatal testing as it's not accurate so no point.
Grow those babies as big as you can.
Prepare for a NICU stay. I have many triplet mum friends and they all spend at least 2-10 weeks in NICU
Prepare and ask for help once they're home. Your husband /partner has to be heavily involved even if he's working. You will be very tired.
Don't prepare too much before the birth as you will see how your lifestyle may change. Ie buggies can be different depending on your lifestyle- I had 9 different ones 😂 I can let you know my favourites.
Don't buy three of everything as you won't need them. Apart from baby bouncers they can snooze in and cots. Your house and requirements will change as they get older.
Get to baby groups and get out when they're babies. It's tiring but breaks up the day. People will stare 😂 and ask you ridiculous questions.
Instagram and facebook groups are brilliant so get on them now. Twins trust is ok too.
As they get older you will need to 100% baby proof your house! Converting the dining room worked for us. And lots of baby gates!
Do go back to work. It's a break even if salary is swallowed with childcare. It's only a short time.
Your relationship will suffer so try and figure out before they arrive how things will work. Resentment is sooo real. Be kind to each other.
You asked for honesty so.... my babies didn't have any long term issues but I do no triplet parents that lost one in womb, one that lost them post birth and some that have long term disabilities. But I also know thriving sets of triplets and quads.
It's a very worrying and tiring time so prepare yourself mentally and physically. But you are capable and you can do it. Most importantly is make sure those babies get fat in the womb!
There are so many wonderful and amazing times as a triplet parent. Each age is different and I wouldn't change it. Experiences will be different than you anticipated but you are so unique. I spent a lot of time regretting and thinking I'd missed out but around a year old I got a triple hug and I knew it was all worthwhile.
Sending you all the best x x x