Garden office- a few questions

Has anyone experience of other suppliers compared to Steeltech.
Looking for a garden room for teenagers rather than home office.

Would prefer options that don't require a concrete base such as Sprout Pod if anyone has gone done that route.
Or reasons to avoid

The concrete slab seems more permanent for down the line if the garden room was no longer required.

Already have a 14 foot hole with two tons of drainage stone under a redundant trampoline

There's not much detail about the steel subframes Sprout use, interested to hear from anybody who has gone that route.

Is there damp proofing underneath or is it installed onto bare ground.

Learned the hard way with our recent Steeltech garage, that they have a new system for the concrete floor. You first pour a frame (like a picture frame) with the center empty. Then they come and put up the shed. Then, you pour again in the empty party, overlapping the original frame as well. Then you send them a video showing how you drive up to the frame and the frame itself, plus pictures of the frame showing the size is right.

This 2-phase pad build is ridiculous imo. You need to get the mason twice, and the second time, they're pouring indoors, which is more challenging for them especially the floating of the concrete as they're doing it whilst, at times, standing in the wet concrete. Plus, I've been cleaning up little bits of stray concrete that ended up here and there in the garage for months now and still not done. Masons did excellent work, but ours was a very challenging job.

I've stopped recommending steeltech to friends as a result. I believe their new system, is for their own benefit as the installer can work very quickly and do multiple jobs/day. Our garage went up in about 1.5 hours including the rollaway door, which was a bit tricky to fit.

Anyway, just FYI hopefully your install goes/went well.