How long is it before he goes to nursery? Unless it's imminent I wouldn't necessarily adjust your routine right now to accommodate them as a lot can change in a few weeks. That said, have you tried just putting him down at 12? The reason I ask is that the first nap is very short and it would not be unusual for the A time after a short nap to be much shorter. You may find he'd be willing to take the nap then anyway.
I wonder though if you could get that first nap longer then you could have the second nap after the 1.45 school run instead? Realistically getting him up by 1.45pm it would be a big ask to get to a decent bedtime without another sleep, if you are doing a morning catnap/lunch long nap kind of routine you'd probably need a 2h nap as a minimum and possibly longer. Does he wake reasonably happy from the morning nap? If you I wonder if you could push the nap to say 9.45/10ish, sleep to around 11.30, then second nap around 2.30/3ish?