Well done on getting one!
I registered my interest with ShopTo back in January but I got an email today telling me I'm not among those who will get one on release day. I'm guessing I wasn't quick enough to hit the button in January. So I'll keep it there for now in case people ahead of me in the queue don't end up wanting or paying for one.
Also on Amazon you can register to be "invited" to pre-order which I found interesting. Not sure if they're going to see how loyal a customer you are (eg length of Prime membership, how often you return stuff etc) before letting you pre-order or maybe they're doing it to try and stop scalpers pre-ordering en masse. Regardless I've registered to be invited, so we'll see.
Argos and Very had pre-orders up but they all went before I realised.
I'll keep trying but may have to accept this could be one of the first Nintendo consoles I won't get on the release date. Such is life.