Going off grid using solar PV alone isn't easy in the UK - we don't get a lot of sun in the winter so you need a lot of panels and big batteries and even then you'll almost certainly need a generator to get you through the darkest parts of the winter.
There is an excellent tool to help you determine suitable panel and battery sizes based on historical solar insolation data:
http://re.jrc.ec.europa.eu/pvgis/Select your location on one of the maps and then select the 'Stand-alone PV' tab. As an example, I tried a London location and created the attached spreadsheet which works out the lowest solar panel + battery cost for three scenarios:
a) The batteries never completely empty
b) The batteries become fully discharged on 2.5% of days annually
c) The batteries become fully discharged on 3.5% of days annually
I selected module inclination of 70 degrees to maximize production in winter when you most need it, 1000W solar panel and increased the battery size until the results showed the battery just became empty on 0%, 2% (ie. 2.5%) and 3% (i.e 3.5%) days respectively.
Selecting a battery cutoff limit of 0% (fully discharged) should be OK because the deep discharge batteries you'd need can be 100% discharged, if not recommended, and would only be fully discharged on a few days a year at most. In reality you would need to use the generator on those days anyway.
I've also attached a spreadsheet of prices of various lead-acid batteries in Europe which calculates the lifetime cost per kWh. I created it a while ago but the prices seem to still be unchanged. You might be able to buy cheaper traction batteries for fork-lift trucks but they don't often have online price lists. You can also buy second-hand fork lift batteries which don't have enough capacity left for a full shift at a warehouse but may be fine for your use. A risk, but OK if they are cheap enough. Buy the old forklift at the same and you solve the problem of moving tonnes of batteries around your property!
The typical UK daily consumption of 10kWh would require at least 41kWh of batteries and 12 kW of panels costing at least £10k (the shipping cost for the batteries is not included in the spreadsheet). On top of that the ground mountings (you could use wood), wiring, charge controller, DC isolators (not cheap), fuses, meters, a shelter/building for the battery and generator, temperature monitor(s), generator(s), fuel storage etc. would be required. Reducing your consumption will help considerably providing you can convince your partner not to use the tumble drier and not to keep leaving the garage light on.
Don't forget to include de-ionized water in the running costs as large flooded cell batteries use a lot of water, although one off-gridder at least, uses winter collected (ie. dust free) rain water apparently without harm.
It can be done if you have space (and planning permission) for enough panels. But don't forget batteries must not be neglected or they can be easily destroyed, although the flooded cells in the spreadsheet are much more robust than the maintenance free AGM etc. lead-acid types. They need to be equalized periodically with an equalizing charge to de-stratify the electrolyte and prevent sulphation and electrolyte levels and gravity need to be checked regularly.
Early deaths of batteries due to lack of experience or neglect isn't uncommon and can blow the financial case. It's not uncommon for batteries to fail early for no obvious reason so you still take a risk. If the cells aren't well matched, weaker cells will suffer as they will suffer deeper discharges and more overcharging than the others causing a gradually accelerating decline. One off-gridder had to fight a supplier to get a pack replaced - she had to prove to them, using her chemical engineering experience, that the manufacturer had changed the separator material and she'd ended up with cells from different batches which performed differently.
And then you have the problem of deciding to replace the whole pack or just the failed cells which isn't a great idea.
And to achieve the < £.07/kWh lifetime battery cost the battery will need to be operating for 20 years or more (because to operate on PV alone the battery is necessarily very large and so has very shallow discharges for the majority of the year). Are you sure you'll still be living in the same house in 20 to 25 years - no buyer is likely to want to take on such a system? Will you still want to be managing the batteries and maintaining the generators in 25 years? Or would your partner want to take it on should the batteries outlive you?
Don't forget the hazards - some recommend having a barrel full of water nearby to jump in when a cell explodes for reasons unknown, or due to dropping a spanner across the terminals and showers you with acid - not unknown.
If you fancy the challenge then go for it - it could be a lot of fun and might even save money especially if you can get cheap or free second hand batteries; just don't underestimate the work and risks involved. I'd suggest organizing the cells into at least 2 parallel batteries if possible so that when you have a problem with one of them you aren't faced with running the generator for long periods until you can get replacements. Alternatively you could have a smaller reserve battery made from retired UPSs or older cells with insufficient capacity for your main bank.
You'll have a large surplus of electricity during the summer so try to devise a profitable use - a bit of aluminium smelting perhaps? Oh and the batteries will have useful scrap value when they do need to be replaced - if they haven't been nicked, along with your panels when you were on holiday. (Ground mounts are more vulnerable than roof mounted panels).
A good UK resource is the Navitron forums which has some experienced off-gridders:
http://www.navitron.org.uk/forum/ 
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