There are either hardwired or low voltage options. The LED bars do have warm (2700k) to neutral (3500k) to sunlight bright (>4000k)

You may find the following thread informative

Here is a link that might be useful: LED UCL DIY

Thanks, I can see we need to do more research before deciding what to do.

Since you have florescent tubes I imagine you would be more interested in line voltage options. The line voltage options will have the transformer built in and will allow you to hard wire the lights. Line voltage LED kits will have a transformer built into the unit.

However they sell a thin electrical box to take the romex to a single outlet that is made for placing underneath cabinets, so if you purchased a low voltage kit you could use that box to take your romex to a plug, then plug the transformer into it, and then run the lights off of the transformer. If your cabinets are next to each other you can use one transformer (if sized appropriately) for all lights. If they're spaced apart you'll have to take into consideration that the low voltage cables aren't typically allowed to be fished in the walls. While low voltage, the current may be quite high so check for codes.

At my local big box stores they carry mostly low voltage kits. But search online you'll see more options. Kichler is a name that came recommended to me but comes at a price.

Use LED under cabinet task lighting..comes in various lengths and are dimmable and are available from kichler...100 for 22 inches...comes in three finishes..our lighting architect chose these for us.