Thanks Dave and DG.
I will try the battery disconnection first, as I wouldnt know where to plug in a dongle

Failing that I will just see my Vx dealer to get them to rectify. PS After reading another thread on dealers reading the codes, perhaps I will not!!

It is not worth driving the 232 miles round trip to see Serek. 
You don't know what has triggered the codes, and it has only happened since having work done.
As I see it's you have three choices:
1. Take it back to Serek to fix.
2. Pay another garage to diagnose and correct it. Which will include going over any work recently done.
3. Ignore the whole thing and hope it goes away.
232 miles may not be "worth it" but the savings you are trying to achieve will cost far more than a tank of fuel. Especially if he hasn't done simple stuff like checking everything disturbed is correctly fitted.
And whilst it is incredibly noble of James V6* to offer to work for near free, that doesn't address the fact that the work you paid Serek to complete has potentially caused issues and as a commercial garage he has an obligation to fix any issues resulting from work done and having anyone else look at it will waive your right to recourse.
Not wanting to over egg the omelette, but if that vacuum pipe had come loose then you could have been left with a runaway engine and no brakes. Whilst driving home with your grandson.
* He hasn't yet and not should he.