Complete beginner

Hello
I'm a complete beginner.
We've got hold of a cheap small polycarb greenhouse and have prepared the ground. I'm debating whether to cover the ground with enough paving slabs to stand the house on and just use growbags inside and staging or whether to leave some earth exposed.
The ground is poor where it will stand but can be improved of course. It's only 8x6 so not a lot of options I suppose but I could sure use some advice please.
Thanks

Jim

Thank you Stompy, this really helps.

The climate here is harsh and my allotment is over a 1000 feet. On the +side it has an open aspect though. I guess I was unsure exactly what the g/h is for. Is it for getting things going to make best use of the short growing season or is it to produce stuff that would otherwise be impossible. Maybe the two aren't mutually incompatible?
Thanks again

I grow in the greenhouse border as I get more cropping height from floor-to-ceiling (and, indeed, I have lowered the border)

I change the soil every Autumn.  "Soil" is a loose term! its 50% compost heap and 50% rotted manure.  The compost and Manure is fairly "rough" when it goes in, but the Tomatoes / Melons / peppers / Aubergines / Sweetcorn etc. don't seem to mind.  At the end of the season its nice and fine, and then goes onto the beds.

Digging the soil out was hard work, and I wish I had done it before building the greenhouse and before the sun had then baked the soil rock hard ... but the Compost / Manure is light as a feather by comparison, so not too arduous.

If you don't fancy changing the soil each year the you might want to look at getting Grafted Tomato etc. plants which are supposedly more disease resistant that ones just bred to be disease resistant.