Hiya My DP Started in the Army the week after I found out I was pregnant. He was at Sandhurst during my pregnancy & at times especially at the start I hated it and him for going. The application process & the run up to them leaving for me was probably the hardest bit, I was a total wreck.
If your only seeing each other at weekends now it won't be too much different if he gets in so you probably won't find him being away as tough as you might think.
My son is now 10 months and iv decided not to live on the patch. I never thought I'd say this but sometimes it's actually easier having a baby on your own. You can do it all your way, sleep when you want - if the house is upside down & you want to spend the day in a dressing gown living off biscuits it's fine as theres knowone there to see it 
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DP was home for 2 weeks over Christmas and I thought I was going to kill him lol. Iv got myself and DS into our little routine & when DP comes home and try's to change it & leaves his crap all over the house I'm thankful he's in the Army!
I found the pregnancy harder than when the baby came because they keep you so busy you don't have time to miss your partner too much. Of course there are lonely days, & times when you might even feel resentful that your at home with a baby having a meltdown they are off skiing (as my DP is currently doing for "work")
but it's honestly not as bad as you think & you Will manage.
Have you got family / friends close by?
Iv filled my days with baby activities & am lucky too have met a great group of friends with babies the same age. The days/weeks go so quickly & since Sandhurst DP has been home every weekend - except this one.
In the run up to him going (if he gets in) there will probably be lots of tears but when he goes your practical side will kick in & you'l get on with things for your bubba.
Hope your ok - congratulations on your pregnancy. Happy for you to PM me if you need a chat / rant
Hayley x