Lol, impressive work mate.Nope its a straight race to get payment authorised. OCUK allocate stock as payment gets authorised, not according to order time or number. Stock is not reserved when its in your basket, you have to be as fast as possible and pay with something that authorises instantly.
The quickest method is to buy ocuk gift vouchers now and have the balance added to your account and ready to go by 1:45pm and start refreshing the page of the cpu you want like a madman. Course if they bump the price up again between now and then you're stuffed so you better get £50 more than you think you need lol.
Second fastest method would be either credit card, paypal credit or paypal balance.
Third fastest is debit cards which have to check your available card balance before authorising
Next its PayPal card processing which has to connect to visa/mastercard, pass through your details and then check your balance.
Finance and bitcoin are the slowest as they need an actual person at the store to bother checking they are authorised before approving payment (or did last time I used either which was some time ago now admittedly).