Hi, Nutjob. I suppose it depends on the school but Y1 (and Y2 at our school) classrooms still have a home corner, construction toys etc. They don't have as much non-teaching help as Reception though, so the children are nannied less and have to be a bit more self-disciplined, but they aren't expected to grow up a year all at once.
Reception is classed as "Early Years" (like a nursery class) and I think the designated formal teaching time is less there - according to our school prospectus (not that I've seen it recently!) teaching hours for KS1 are c 21 hrs a week and KS2 c 22 hrs a week, or a bit over 4 hrs a day, and they are at school for 6½ hrs, so there's quite a bit of non-teaching time.
They do get the numeracy and literacy hours of course but I don't know if they still do an actual hour (they did when the scheme started). That might be the biggest hurdle - but even then the period is broken up into different activities.
Honestly, I wouldn't worry if you can manage it, settling into Reception is the hardest part. Having a different teacher might bother him a bit, if he has got very fond of his current teacher, so if you can find out which teacher he's likely to get and make encouraging remarks about her that might help. FWIW my kids were always dead excited about changing class at the end of the year - they like to feel they're getting somewhere! If you can talk positively about being a big Y1 it should help, but they are only just over halfway through the year, I would wait until after Easter or even May halfterm. Good luck! I'm sure he'll be fine!