Thank you everyone for your help/advice ive purchased a new battery
A7 Varta Dynamic AGM 096 Start Stop Car Battery 12V 70Ah

Battery makers have got pretty good at making them just good enough to get through warranty. Even the 5-year Hyundai warranty only covers the battery for 2 years. I first replaced the battery on my 2015 diesel at 3 1/2 years old. Next battery (Yuasa) lasted for 5 1/2 years.

If you let the battery go into deep discharge, like leaving an interior light on while you're on holiday for a week, the battery can suffer permanent damage and will never be the same again. The voltage from the alternator will look fine because it's being regulated, but the battery voltage will sag significantly if you try drawing any significant current from it, like when starting.  I've always bought Yuasa and if you shop around there are usually good deals out there. If you can find one local that's better because if you get problems with the new battery you can take it back in person instead of having to return it by post.

The batteries age im unsure, ive had the vehicle 2 years , and its done 65K miles, 1.6 diesel , 128bhp its a 2014 (64)

Ok, unknown age of battery just adds an element of mystery.    (EDIT.  There are numerous videos on YouTube about battery date codes, if you're interested).

You originally posted that the car was unused for two weeks and when you tried to start it, the battery was dead. My first thought was the battery may have a parasitic draw/drain.

You called "recovery" (a vehicle breakdown service?) and they checked the battery and the alternator and said they were ok?  I understand how the alternator could be tested and be diagnosed "ok" but not how the battery could be checked as-is and be definitively called "ok" (because it could be jump-started?)

You drove for 20 miles and then the battery wouldn't restart the car.  My thought was either the battery has one really nasty, nasty parasitic draw or, more likely, the battery is defective.

Then, going by your posted sequence of events, your neighbour checked the battery with a multimeter and it read 4.5V and after charging the battery overnight for approx. 14 hours, it only read 6V.  If the battery was charged while in the car, the battery is defective or it could still have parasitic draw from when the the car's computer modules fail to enter low-power "sleep mode" and remain active, drawing [significant] power overnight, but unlikely.  If the battery was charged out of the car, it's not parasictic draw, it's a defective battery.

Sorry about my mixup with your vehicle model, I confused yours with "eye30"'s vehicle. 

Sorry for the ramble, it's how us senior Virgo's collect our thoughts. 

The batteries age im unsure, ive had the vehicle 2 years , and its done 65K miles, 1.6 diesel , 128bhp its a 2014 (64)

Think you need a new battery.

 I think so also.  BTW, you didn't reply to how old the battery is (and its mileage would also be helpful).  I don't know anything about 1.4 petrol Active models, so if the model is within say, 2010-2015 and still using its oem battery, you've had a great run.