ks, you have to pick Christmas deliveries from the groupings of slots and as cod says, then park a trolley-load of stuff there to keep the slot.
Mine is evolving towards its 23rd December delivery status...
If you are pressed for time, stick four bottles of bubbly in it to take yourself over the magic £75 and come back later.
What clinches it for me with Ocado is the local factor. Some people clearly get on OK with Tescos but our local delivery service from them is truly atrocious, as is our Sainsburys Sod You. We've tried both and it's so bad it's like having your shopping thrown at you, what there is of it.
Ocado aren't perfect but I do have a major ethics problem with Tescos in general. We're lucky enough to be able to afford the debated "extra" costs of Waitrose produce and groceries to account for the fact that they source regionally, then nationally, treat their suppliers decently and rack up the profits on fair trade less than any other supermarket. We get houseware bogoffs from our local Co-op and would shop there more if it also wasn't rubbish.
Since I heard about the grape producers I decided to boycott Tescos I feel it is the last straw with them. I hate them too.