R/O Units in the UK

A lot will depend on your water right now. If it has detectable nitrogen, metals, or phosphates, using RO water will reduce the headaches you'll have dealing with algae. It will make it easier for you, more than anything.

Most of the units are fairly straight forward to setup. The biggest complaint I see relates to user error--ie, turned it on, and left the room, forgot, flooded the house. There are ways around this, so just plan in advance by having the tub sit in the sink to fill, or purchase a water detection alarm.

Not sure on cost--maybe Oakley or one of our other chums from across the pond can chime in?