Hi Luke
You appear to have two problems, hard water and low mains pressure!!
Before embarking on a search for a water softener you should sort out your water pressure! If you had a tank in the loft then a water softener (Harveys or Kinetico are the best) will present no problems because the water is fed through the softener to your tank and water pressure at the incoming mains is not really an issue. However many people have combi boilers installed that do away (sadly) with the stored water in the attic. It was the stored water in the attic that would have given you sufficient pressure in the house.
So, you have a combi and this is where you problem starts if you have low incoming mains pressure. Have another look at the mains stopcock and make sure it is fully on. If so, and you still have poor pressure it could be worth a call to your water supplier with an observation that you have poor pressure. I did just this last week having moved into a new house and complained to the builders of poor pressure. They inspected the internal plumbing and said all was OK. Call to the water supplier brought an instant response, checked mains pressure - very poor. Removed water meter filled full of builders' sand, cleaned it all up and replaced with new meter, mains pressure now fabulous! Previous meter had not been reading so 6 months of free (low pressure) water.
Have now installed my Kinetico (20 years old) and we are back on soft water.
If you have poor water flow then the Harver softener will be your best bet as they do not slow the water flow as much as the others out there.. Do not try to do it on the cheap and get a box from one of the sheds and get your plumber to fit it.
If you do not like scale (me neither) then consider a (good) water softener to be a long term investment and get the people who make them to do the install. They do this all the time and know exactly the best place to install it and will give you a guarantee. They will check your water pressure and tell you whether the install will give you more problems with your water pressure, bearing in mind that there will be some reduced flow as the water passes through your softener.
For info the Harvey (also sold under other names - MiniMax, Crown etc) is designed for both high flow and low flow. The Kinetico on the other hand is sold as HF (High Flow) and HE (High Efficiency). In order not to reduce your flow even more you will need high flow connections between your house plumbing and your softener. But the installer will know all about this and fit them automatically.
Good luck with your challenges, remember do not go for the cheap option, you will regret it!!
