(before Bella explodes)
the short answer is, you can't. It's not going to work with puppy pads three days a week, and the back door for the other four days. Even if you spent your four days diligently putting the dogs outside every twenty minutes, rewarding every outdoor wee, showing them where to go, etc, the moment you go back to work and leave them alone, they'll be trying to do what you want, and not being able to. Dog flaps might be a solution but is your garden completely safe from chew hazards/poisonous plants/potential dog thieves?
This is the basic time table I had to follow to house train my puppy:
7am up - outside to wee, reward
7.15am - breakfast
7.17am - outside to wee again, reward
7.30 am - post breakfast snooze in crate (dog, not me)
8.30am - outside to wee/poo, reward
8.45am - sit training, playing
9am - outside to wee, reward
9.15am - snooze
10am - outside to wee/poor, reward,
etc, etc, etc all DAY. Wee opportunities on the hour until he was reliable enough to tell me when he wanted to go - it took nearly four months and I was home all day, carpet spray in hand, and he had an adult dog to copy.
Sorry to sound critical, but I think you're heading into a minefield. Two puppies is a handful even for experienced owners, because each puppy needs their own training/socialisation time to stop them bonding with each other, not you. Also, they're going to take longer to house train if you're not there all the time to reinforce the routine, and if your DH isn't keen now he'll be even less keen when they start chewing out of boredom, as well as smearing the house in dog poo. Terriers need masses of stimulation as well as firm boundaries.
Can you get someone to come in during the day, or is there a puppy daycare facility near you where you can drop them off? It's not going to be a cheap option, but it might be cheaper than coming home to find your kitchen shredded!