Cat flaps in sheds

[WhileMyMeringueGentlyWeeps]

I have two year old cats who have discovered the great outdoors this summer and now stay out all night. They sleep in the garden border or down the side of the shed if its raining but they really do seem to prefer to be out rather than in at night. This may change when the weather gets cooler obviously but I am thinking of putting a cat flap to the shed so that they can shelter there in bad weather or just to avoid neighbouring cats or foxes. I rent so can't have a cat flap to the house.
So, is a microchip one necessary? ££££ Or will I find all the neighbouring cats in there having a party?
If I put food in the shed will there be vermin? Will my cats go and live in the shed permanently and I'll never see them?

Do it. I don't think a microchip one would be necessary but you can always change a normal one for a chip one later if you feel it would help. And if the cats are in there you're not going to get mice. And they will definitely be back indoors when the temperature dips.

Personally I wouldn't leave food outside in the shed - you'll attract all sorts.

Water and a bed should be fine for overnight and they can come in and eat in the mornings.

Do it....we did just in case our cat refuses to come in at night!

I'd always go for microchip or we'd have all sorts of visiting cats! I definitely wouldn't put food in the shed.

You can buy outdoor cat houses. Might be a better idea than putting a cat flap in the shed?

We put a flap in the shed for our old cat who promptly refused to use it. Our new ones sleep in it all the time and I ended up putting a cushion on the shelves. Yeah I know. Cat slave.

I insist the cat comes in at night because I worry but she has one of these for when we're out in the day, and she loves it.
Leaving food is a bit troublesome because it'll attract other cats and rats etc.
Cat house

At my last house, I just cut a hole in the shed door. Like a big Tom and Jerry mouse hole.

I have a non microchip cat flap in the shed and never had any cat in there including my own! 🤷‍♀️ I don’t put any food in there and I think if you put food you’d get all the cats and possibly mice/rats.

Haha loving the cat house. However my garden is small and there's a massive shed in it the cats could use for less than price of a cat condo.
I shall investigate cat flaps.