Hotstock is another app to try if Discord isn't your thing. Simply install it, make an account then select the products you want notifications for. Its a few mins slower than Discord but it gives you a link direct to the product page.
The stock has been available on one retailer or another everyday for a few weeks now. You just got to be quick.
Argos is the best bet, just make sure you're signed into argos with all your payment details already on your account.
When they get stock they update each warehouse individually, usually starting from the North West, then London, then about 3 hours after the 1st one in the NW becomes available they start popping up round here. Just keep an eye on it, refreshing every fee mins as if its deadline day on the day you get an argos notification.
I got 3 kids, 2 want the xbox and the other the PS5. Started looking last Thursday and I've got all three. First time I've ever been this organised for Xmas!!!
Did the same thing in Jan to get myself one.
Just keep an eye on one of them 2 apps and you'll sharp get one.