Permanent opening to loft??

I'm in the process of converting my loft into a storage space. I've got someone coming round to strengthen joists, board it over and fit a skylight.
It seems a shame though to have all this extra light coming into the house via the skylight, but for it not to be seen. I was wondering therefore, is it possible to have a larger loft opening made (approx. 1.5m x 1m) and have it permanently open to the roof space above to allow the light to come down into the stairwell below? How would this fit in with building regulations??
The loft would only be used for storage and would be accessed by ladder. I would ensure that no one could fall down the hole, by adding banisters/railings around the top.
If the loft opening was permanently open to the roof space I'm assuming that insulation would be a big issue - the only problem is that I've got shallow rafters in the roof (approx 10cm deep) plus I want to retain as much head height as possible so what's the best insulation to use in this situation?
I haven't been able to find any info with regards to loft openings and building regulations - so any advice would be greatly appreciated!
Thanks!

1x1.5m seems a bit big but allowing any alterations would require some calculations that we cannot workout without seeing/knowing what's involved. The person strengthening the joists, is this being done based on any calculations or just a builder who says it will be fine? Taking a little step back from what your doing, why did you want a skylight if its just storage? This seems like a bit of a waste of money for storage unless you plan to change this down the line? Not sure why you would need banister/railings if this is only accessible by ladders that would only be there when your using the room for storage as it would just be like any normal loft space that has a hole for access with some ladders to it.
Yes having a big hole in the ceiling is going to cause you extreme heat loss and potential dust/crap in your hallway. How is the inside of the loft underneath the tiles finished? is it just felt backing or has this been boarded out (or will be + insulation) or just bare tiles? How many floors does your house have? Do you know if the loft floor will be 4.5m above ground level?

Not much point in insulating the ceiling if there is a ruddy great hole in it?
Although I guess that you could insulate the roof rather than the ceiling/loft floor?
However you're heating twice the area

Look up
http://www.velux.co.uk/products/sun-tunnels?gclid=CL_DiavuqNICFQEA0wodFvYI3w

Etc

They are shiny tubes that have a window at one end and a skylight at the other, giving natural light where you want it

if you want more light why not fit a sun lite tunnel

sorry just noticed above post doh

Once you create a permanent opening into the hallway, you would then effectively be doing a loft conversion, and then be required to create an escape corridor to an exit, so this isn't a goo idea. You mention the shallow rafters, and the problems with insulation, but if the builder is reinforcing the joists properly, then there should be enough depth for insulation, and the bedrooms at least would then be fine, but you'd still have heat escaping into the loft, and that would then give you condensation problems in the roof space.

Find out how the builders intend to expand the loft hatch, and how they intend to reinforce the joists. I think like others have suggested, that the sun pipe is the best idea to get more light in to the hallway, and there are cheaper options than Velux available.

Thanks all for the input - It was just an idea, so thanks for all the advice!
I hadn't thought of a sun tunnel thingy - so I'm going to look into that!