We'll see how it works this weekend I hope. I had quite a bit of fun doing this...
Some lessons I learnt that might be of use to anyone attempting a similar sort of project;
The electronics is fairly simple, but I'd recommend getting the single board form ArdBir. It looks well made and easy to wire up so it should just work.
LCD module datasheets can be a bit vague regarding backlight power supply. Check the module to see if it has the current limit resistors in place. Mine were 0 ohm so I needed an external resistor.
Hole saws form screwfix work fine in stainless. Go slow and lubricate well.
Cutting gaskets from silicone sheet is difficult with a knife. Get some saddle punches, they are cheap and work well. Alternatively, use a bit of pipe sharpened with a file.
Probably worth getting the upper and lower filter plates made by someone like Inoxia ltd. They trade on ebay and this will save a bit of work.
Stainless is ok to solder using plumbers solder and flux. Just make sure it's WRAS approved/lead free and clean it in hot water after.
Ockelford, the braided hose I used is a a standard type tap connector from b&Q or screwfix... it says its WRAS approved for potable water to 85C so should be fine. Ill do a full flush and clean tomorrow and if it seems rubbery I'll replace it with silicone hose and fittings I got from solarproject.co.uk. The fittings are 1/2 BSP and will fit with no modification.
Tata for now.