As a military wife for many years, I can say that you will cope. You have the added benefit (I assume) that you’re DH isn’t in a war zone and in a life threatening position daily for 9 months. I don’t mean that to sound harsh but i’m trying to say you will be fine and as a mum to two, you will become a really strong person.
For the kids and their dad, we found that letter writing (dot to dots drawn by my DH/ bunting he drew that we could peg up in the playroom/funny jokes he would send back) and recorded bedtime stories really helped the kids to have something to look forward to. We had email and phone etc but having something to see in their hand somehow meant more than the odd weekly phonecall.
Without any extended family nearby and being in the middle of nowhere, I had to make sure I organised something to go and do on each weekend day....even it was a trip to Tesco or the hair salon, to make sure we left the house.
Rather than a nanny, could you get an au pair? That way, they’ll be living with you and there when you need them. Many do weekend/night babysitting for extra pay, giving you time for yourself too.
Running the house will work itself out too. You’ll quickly find shortcuts.
-Have laundry bins for each person. Wash and dry each bin separately. That saves on time sorting through mixed up washing.
-from spring onwards, find a local teen who will cut your grass every weekend.
-On 1 or 2 of your work days, have a cold, buffet style tea. As long as you’re giving the kids the required nutrients, you don’t have to have slaved over a hot dinner.
-If you can afford it, take the kids out for tea once a week.
-Don’t feel like you need to bath them every single day.
-If you have in laws/parents who can take the kids for a weekend, let them crack on. Then you can do a mix of relaxing and deep cleaning.
Try not to worry. Do you know hw long your DH will be working away for at a time?