Thanks for the opinions, all. I thought that might be the case.
Yes, I'm Parent B at the moment.
However I was both Parent A and Parent B for a term and a half, until I had a near nervous breakdown, so I don't feel too guilty about it. I was being a nincompoop and didn't realise that there was another option.
Luckily (or not) my work allows me to catch up on evenings and weekends, so I was putting the boys to bed then getting my laptop out for several hours in the evening, and then being stressed about 'catching up' over the weekend as well.
So now we share.
But the problem now is that DP is incredibly bad at managing the morning routine, and is late to work pretty much every day - it's a running joke among his colleagues now, with bets running over what time he'll come in!
This really isn't ideal, but the only answer as far as I can see, is for him to get up earlier, sort himself out and get out of the door on time, at ten to eight. As it is, I have to wake him up, then help with brushing DC's teeth and general cajoling, so it makes me later than I'd like as well.
I've offered to swap on a few mornings so that I do drop-offs and he does pick-ups, but he's still trying to muddle through. I think we'll get through this term and then have a think about what a more manageable routine might be, post-summer.