The house is very bottom heavy and unbalanced.
As pp's have suggested you'd be far better off with 4 bedrooms and only one en-suite.
The dining room will become a bit of a dark dumping ground.
I'd knock the playroom and that together so you get light in - remember you won't need a playroom forever so that in time could become a dedicated dining room if you want.
I'd also suggest that the whole back extension is massive in comparison to the current footprint. You may struggle with planning and I'd question how much garden you are going to lose/have remaining.
If you have a huge back garden then maybe not an issue but if it leaves a small garden then that's not attractive for a family home.
Tbh it look like you've drawn this up and the whole house just don't really flow properly or balance.
This is why if you are planning a massive revision you really need to invest in an architect.
If you do, you'll also be surprised at where they can find existing space from the current footage and seamlessly incorporate a new extension.
As stands it feels like you've drawn up what's perfect for you now without thinking longer term about your needs and also re-sale and I think it's likely to be less a dream and more of a folly if I'm honest.
Admire your ambition though :-)