It is a minefield as under UK Consumer law the retailer only has to pass on the manufacturer's warranty (forget the EU 'regulations, the UK has never adopted them as they are still in directive status).
if there was an issue after this 12 months then the supplier (who you bought the phone from, say Argos) would be responsible to a repair/replacement.
The problem is that you as the consumer have to prove, under law, that the fault was inherent during the warranty period and only manifested itself with the 'reasonable lifetime' of the faulty goods (Apple quote three years life expectancy for an iPhone).
that could be something difficult to prove and get Argos to accept in this scenario. If you had bought the phone from Apple directly, you would have an easier time getting them to fix it as the onus is on them as the supplier.
with the JL 2 year warranty you get piece of mind for not having to deal with such issues in the first 24 months of owning the phone.