My point is that the 2nd vaccination must be given at 12wks, now that the vets here have switched to Eurican.

See here, Eurican:  http://www.noahcompendium.co.uk/Merial_Animal_Health_Ltd/Eurican_DHPPi/-31357.html

"Primary vaccination:
1st injection: from 8th week of age.
2nd injection: 3 to 5 weeks later, from 12th week of age."

This is completely different to, say, Nobivac, where you have:  http://www.noahcompendium.co.uk/MSD_Animal_Health/Nobivac_DHPPi/-29490.html

"Primary course vaccination: A single injection should establish active immunity to canine distemper, infectious canine hepatitis and disease caused by canine parvovirus infection in dogs of 10 weeks of age or older. Where earlier protection is required a first dose may be given to puppies from 6 weeks of age, but because maternally derived passive antibody can interfere with the response to vaccination a final dose at 10 weeks of age or older is generally recommended. For an optimal response to the parainfluenza component, animals should be vaccinated twice, 2-4 weeks apart with the final vaccination at 10 weeks of age or more."

Vets are only following the advice as laid out by the vaccine manufacturers themselves.  If they switch to a new vaccine brand, they will also follow the different guidelines.  Although all this is a load of rubbish because the vaccines are essentially the same, interchangeable and function in the same way, so there's no known reason why it would be ok to give one brand at 10wks but another brand you'd need to wait till 12wks.

Mine are jabbed at 8 and 10 weeks.
I try to get them out a week after their first and all my other dogs go to shows and other public places then mix freely with the babes.