[CherryBrandy]

ok misty moo ! welcome to the site and ask away. Particularly about lighting as each set up is so different and we all learn on here. so is that 4ft by 2ft in old money?

Halogen is good as a heat source basking lamp but won't of course provide the vitamin D / sun levels.

160W is huge for that area so can see why you want to change.

You either need a combined UVA&UVB - Arcadia D3 is good for that.

Or a tube light set up with UVA&B....this will provide the UV but wont add much to a heat/basking lamp so you then need heat ! and halogen is probably ideal. or anything that says basking light.

so to recap in simple terms - you need sunlight and heat.
A) UVA&B combined provide the sunlight and the heat. or ....
B ) Tube provide the sunlight (make sure sufficient UVA&B levels) then any type of
basking to provide the heat.
on both A or B make sure you have a cool down end as constant heat (source) can be a killer. And make sure its not just an A UV light as this wont wash with providing the right UV for a tortoise, shout if still confused as it can seem complicated when stating out.