I have an old water tank that I use as a water butt in the garden and I want to put a tap in the bottom of it for a hose. Is there a tap that comes with a fitting that will allow me to drill a hole in the tank and then (I presume) screw up two bolts either side of the hole before fitting the tap.
This is probably a terrible description of my requirements but hopefully someone handy understands it.
Cheers

I didn’t really understand it (but then I’m slow).

Is the issue that you want to fit the tap whilst the tank is full of water?

A water butt tap will fit in the way you describe. They are generally a bit cheap and plastic, though. eg http://www.wickes.co.uk/water-butt-tap/invt/194488/