I cant think of a tool tht works similar to the patch tool in photoshop.
Any ideas of a substitute way of working?
The thing about the patch tool is you get to drag the selection around to choose the area that is going to be used as the replacement pixels. I find it much quicker than using the clone stamp and great for old photo restorations.
patch tool demo
So far I am making a selectin then using the resynthesizor plugin but that only gives you the choice of using pixels from above, below, the sides or all around.
The Healing brush doesn't give me good results ( a bit blurry). so I tend to use the clone stamp in preference to it.

do the selection
create a gimp brush from that
paint with that brush

Use Healing Tool or Clone Tool. (In some cases both should be used in combination)
Use a soft brush
Make a selection (Ctrl + click to set a new heal source)
Set the alignment to Fixed.
Brush on the target areas.