if you have white smoke out of the exhaust, and you are losing water, then thats a big pointer to the head gasket. Added to the fact that you say there is water squirting out the expansion pot, then its deffo the gasket, the cylinder is pressurising the water, causing it to squirt out.
The first thing to do is get the gasket sorted out, then we can see what other problems persist, and which ones go away.

bollicks!!!! its pritty much engine out job i take it? il manage t do the job ma sel just need to know how hard it is to do?

you can do it with the engine in the bay, its fiddly, but doable. probably easier to do it with the engine out, but its the hassle of taking the engine out which probably will make it easier and quicker to do with it in there. Doing it yourself is ok, but you will need to see if the heads or blocks need skimming.

just goin to price gettin new engine. got engine hoist etc at home so will manage to take it out. havin to bmp start it in mornins just now battery has started dischargin its self so its a sign to get her off the road and give her full treatment. and then recondition old engine as spare

expensive choice, doing the gaskets would be simpler and cheaper. Pressure testing each one of the cylinders will tell which one you need to do.

managed to find a wrx engine with turbo the lot for £600 ready just to slot in with under 80k on it (mines 170k) so il take old engine and sort it and sell it on in time. a mate told me tonight he had same problem with his so he just swapped engines. fingers crossed it will work

b4 i get new engine
 

i was out at garage the other day and guy there said it might be my fuel pump thats causin it to stutter and not power (fuel starvation) its not using any water any more or smoken out exhaust. think it could be fuel pump?

can you hear the fuel pump priming when you turn the ignition on??
If the fuel pump isnt priming then the car wouldnt start at all.
you need a fuel pressure guage in the fuel line to be sure.
However, you can change out the fuel pump and see if that helps at all, its not a massive job to do.

ye i hear it priming when i turn the ignition on, guy at garage said it might nothave enough pressure when getting to last cylinder. said its cheapest option t do first a4 i try engine

that could be the case, you can prob pick up a second hand good one for a few pennies, takes about half hour to change.
Do that and see how you go.
Are you still getting white smoke, and water squirting out the pot?
If you are then you are flogging a dead horse, the gaskets need doing. That on its own will give you miss fine problems.

no its not using water any more wich i find strange and its not smoken. the car has a mind of its own i think. priced a walbro 255 pump for the same as a new standard one so il get it if ts new i know it will work

get a lend of a pump rather than just buying a new one - no scooby mates near you? that you could swap pumps just to try?

i av got couple o scooby mates but they wouldnt lend ma a shot grippit buggers, its only £75 for pump