Concrete floor of porch - Groundwork & Foundations job in Lichfield, Staffordshire

2concrete floor of porch

Job Description

The floor in our porch is slabbed and then on top has wooden joist with polystyrene in between - to get the floor level up to the same level as the door.
This feels uneven when walking on it.

I would like to have this concreted to this level.
I assume that to do a proper job, you would need to remove the slabs and put down a membrane before concreting - please advise.

The floor area is 1.3m x 1.9m
Hopefully the attached pictures will make it clearer.

* The following information was added Thursday, 2nd July, 2009 :
I've been advised that it would be simpler (and cheaper) to put boad over the existing timber and then tile over it.

I'd be interested in a second opinion on this and any revised quotes for doing this -