Can I eat this the cold next day?

[SnowMoss]

Forgive my ignorance, i have only ever eaten roast chicken warm, and am relatively new to it after a lifetime of being veggie.

i would like to buy a 2 pack of organic chicken breasts from m&s, and cook them in the oven. I would preferably want to eat one on a sandwich the day after, is this possible?
If so what are the steps to make it safe?

I have this urge to eat a cold chicken sandwich with mayo but don't want to do deli meat!

Let it cool down then put it in the fridge wrapped in foil. Slice thinly for your sandwich the next day.

Yes its fine. Cool.the chicken down before putting it in the fridge to cool then eat next.day. can last 3-4 days after. Cooking.

Thanks!
Why need foil? Could I use a clippy box?

How long is the cooling safety 'window'?

Can I also ask.....

I left my fridge door ajar about an inch by accident this afternoon.
The chicken was in there, unopened in it's sealed pack for 2 hours until I found the door open.

I am assuming this is still ok??? - it was cold and nothing seemed amiss.
I also often shop on foot, and take an hours walk with it so presume it will survive a slightly open door if it can survive a summer walk in my rucksack!

I don't use foil anything to cover either a tubberware box or a bag or clingfiilm you should let the food cool to room temperature first before placing it in the fridge