What water softener/filtration system to go for?

It's quite simple, I fit a filter to the cold water tap pre softener so you get pure filtered water to the cold supply and soft water to the rest of the house done it Many times

Scale reduction does what it says on the tin, reduces the scale, not remove it. It changes the form of the calcium particles making them less likely to stick to surfaces, but the calcium is still present in the water. A salt based softener will actively remove the calcium entirely. I would strongly recommend a non-electric salt based softener as they are lower maintenance than the electric variety. Furthermore should you move house you can take it with you which makes the investment more appealing. With regards to your kitchen tap, just keep the cold side on hard water, no filter needed as I presume you drink the mains water already. The hot will be softened along with the rest of the property. I hope this helps.

If you have very hard water, you'll need a salt-based water softener or alternative solution. If your water isn't super hard, a Salt-Free Water Conditioner is a great option that requires less maintenance and won't strip away healthy minerals from your water.