OP, I have a husband who I’m quite sure has ADD or something of the sort. He also procrastinates endlessly. Fortunately, he is very detail-oriented and conscientious on financial matters, like taxes, because he’s an accountant. For the other stuff, I set a date by which it needs to be done (always a few weeks before it’s actually due), and then tell him, “Either you can deal with this paperwork, or you can watch the baby. Which do you prefer?” That way it gets done. I live in the US, but DH travels for work, and even without that there always seems to be some sort of paperwork that needs doing: a county alarm permit, filing receipts/health information, filling out insurance documentation, and so forth. These things sound minor, but they take time, and they really need me to be able to focus on the task at hand without a baby screaming for my attention.
Lastly, I don’t remember how old your baby is, but it won’t hurt him to learn that Mommy sometimes needs to spend 15 minutes dealing with this stuff. DD (15 months) used to throw a fit every time I sat down at the computer. This became utterly ridiculous, because DH would need me to scan something and email it to him at work, and it would stress me out beyond belief because just spending that five minutes on a simple project meant a long screaming fit from DD. I finally decided that DD needed to learn to entertain herself sometimes, and now take about 3-4 10-15 minute “breaks” per day in which I’ll either just relax with a cup of coffee and check my email, or get this kind of thing done, or some combination. She threw some absolutely world-class fits the first couple of days I did this, but calmed down after that, especially when she realized that a) there were some really cool baby toys sitting near her she could be playing with rather than throwing a fit, and b) that after my break, I’ll take the time to sit on the floor and play with her for 15 minutes or so.