Loft Access

Build yourself a spiral staircase. It wouldn't be that hard to do. You just use a steel pole in the middle, timber blocks between the treads, timber balusters, and laminate the timber in place for the handrail.

edit : - There’s stair kits here, but you wouldn’t have to use their kit. You could just build your own using their ideas , or you could tackle something like this.

I saw a guide on the net somewhere a while back where some bloke made one and it was solid. I'll try to find it again if you want.

Or you could build an alternating tread staircase, with either open or closed risers. That's probably what you're thinking of as a cross between a ladder and a staircase. I don't know what the regulations are, but they look safer than those flimsy pull down attic ladders.

Spirals take more room than standard in the end.
I had thsi in a place I built in the early 90's. After much agonising I used what is called a step ladder which is a very steep staircase. It passed code as it was based on industrial specs. Bl00dy dangerouse though for litl kids and oldies, and a bit scary coming down. Usually backwards is the way to go. I also looked at collapsible ladders wich take up the space needed to get it unfolded and down on the floor and are pretty expensive unless self built.

I put many hours of thought into this over the whole job and only decided and built the solution in the last days of the job.

If they're not banned here (they are in most countries), you could put in a paternoster I had a ride in one of those crazy gadgets when I was in Europe 25 odd years ago.

If your finances don't stretch that far, and you're really pressed for space, then just cut a hole in the floor, hook up an electric block and tackle to get up, and a fireman's pole to get back down nice and quick.