I adopted a 9 month old mexican rescue mutt, she was painfully undersocialized and timid (but so loyal when she warmed up to us), rather hyper, was a horror to potty train, chewed every piece of paper or plastic she could find, howled when we had to leave (only for a month or so but it was a good six months of chewing)
I was not working at the time. (My SO was) As and someone who has spent a lifetime researching and preparing for a dog, I thought I was prepared for an older puppyhood (and to deal with her issues!). But nope, 9 months she was just as much of a destructive dynamo as ever, I can not imagine having to work at that time, and juggle taking care of her.
Now that we both work full time, and a huge amount of time and effort, she (3 years old) is the perfect dog, she turned out calm and low energy, a good run and she is set to nap the day away. She is still a little nervous, but people love her, she is an obedient, smart adorable little sucker, if I were to pass away, about 10 people would fight to the death over who gets to keep her. I share my story to prepare you for what you might be in for, and my own personal epipheny that I were to get another dog, it would not be younger then 2 or 3, and I may not be so gungho to deal with those issues (Esp now that we both work full time!)
Don't let the corgie in him fool you, they are working dogs as well, so this little guy could very well end up with the stamina to work all day and still want more.
It's commendable you are looking to make the right match rather then getting the first cutey.. honestly I would stay away from both breeds, unless he is the exception to the general rule, and also if the nervousness persists, it's a huge undertaking because socialisation should happen really young, when they are older it can be such slow going. Separation anxiety is really hard on all parties, the dog, you, and the house.
All that said, only you will be able to determine what you can handle, and what this pup is really like! Good luck!