all those bushing and bearings have started creaking what grease do i have to use when i strip it down please

Lithium based.

If the bearings have got as far as creaking have a good check to make sure they don't need replacement , mine started to creak just before they started to collapse.I thought the cones were loose but it was the swingarm moving 😳

I assume its a Halfords special GT i-drive 5 XCR with a Truvativ Firex chainset?

There didn't appear to be a problem with creaking on the original GT i-drive so I don't think it's a feature as some people suggest.

I had the same problem (loud creak) and could not disassemble the i-drive to grease it because one of the pivots had been overtightened. I took it back to the shop and it took 3 of them to undo the bottom bracket style pivot bearing which came out stripped. They replaced stripped parts and bearings and it was quiet for the first couple of rides but has since started to creak a little under heavy load. I doubt its the i-drvie bearings as everything has been changed so I now suspect the crankset.

Other possibilities
The frame has not been faced properly for the bottom bracket
The bolted dropouts need greasing.

Take it back to the shop if it's still in warranty because the parts are expensive if you have to pay for them.

Have a look at this guide from GT
http://www.gtbicycles.com/CMS/documents/GTSuspensionFrameTroubleShootingGuide.pdf

This is the grease I would use
X-tra Heavy Duty Bearing Grease Marine Spec
http://www.dukeriesengineering.com/10325/info.php?p=11&pno=0

thats great i shall strip it and have a look tomorrow thanks

try the dropouts 1st, mine was creaking like a bu##er, regreased them – silence!