SHOWER PRESSURE

I have finally converted the bathroom after the wife nagging for about 10 years and as we have never had a shower fitted before we actually bought a gainsborough es550 8.5kw shower a few years ago in anticipation.
All we have is a cold water tank above about 10 feet in the attic.Its a single inlet only shower
Question is will there be enough cold water pressure from the storage tank in the attic to make it worthwhile or have i got to run it off the mains inlet from the supply going into the cold water tank.

any help greatly appreciated

Read the instructions?

8.5 isn`t gonna do much put it on eBay and get a 10.kw and a sparkie to fit it...........most diy sheds have leaflets on installation before you buy

Before you go too far, work out the increase in your energy bill as it will increase depending on how many showers each person per day.

I'm removing mine and going back to a Mira gravity fed system as I already use gas to heat water for domestic use so why pay for more hot water from a shower.