We have a rather crap patio in the back garden - there's a slightly sloping concrete bit right by the house, then very uneven slabs before a step down to the lawn. The edging is broken and uneven. It's been on our list of things to get sorted since we bought the house, and I think we might be getting to it this year. Ideally I'd like to replace it with something that's level as a very basic starting point, possibly slightly raised up compared to where it is now so that the slope in the concrete can be evened out and we step from the house down onto something flat! There's actually another stretch of concrete about the same size beside it, (but round the corner of the house heading to the back gate), that will also need dug up and re-poured to get rid of the cracks in it!
Can anyone give me a ball park of how much it might cost? It's maybe 12 foot square for the patio and we're in London. When's a good time of year to get concrete in the garden dug up so as not to destroy my plants with dust? What's a good paving slab to use? Should I advertise when it's getting done in case anyone has a body they need to hide 
? I have no real clue about this sort of thing, other than that I'm fed up of the crap one!