Posted: 24/02/2015 at 16:33
It looks as though the existing path is just slabs. If so, you (someone!) should be able to lift them. If the path has been laid properly there will be a load of hardcore underneath which needs to be dug out. If you like the slabs and need to replace any broken ones near the shed or extend the paving in that area, there is no reason why you couldn't reuse some of the hard core and path slabs.
From the photos it looks as though the existing lawn is quite small and full of weeds. If you are extending the grass area you will need to get it all of a level so I would be tempted to strip away the existing grass so you can prepare & level the whole of the proposed lawn area as one piece - you will get a much better lawn that way.
That is quite a bit of hard physical work there. Not particularly skilled work (except for laying the paving) but hard graft. Can you bribe some muscle with the lure of beer & BBQ?
Make sure that any paving / stepping stones either up to or set into the grass are about 1 cm below the grass level. If they stand proud you will not be able to cut the grass properly & will forever catch the stone with lawnmower blades.