The glow plug was picked up on the last scan as one was faulty, but the mechanic said to leave it as it can be a big job if they get stuck. He did say it's minor as it's not causing too much issue. Battery is most likely few years old. Will check bit later+++

If it's flagged up faulty I'd get then all replaced.
Mine use to struggle in the cold, replaced fee plugs and made massive difference.

Plugs are not that expensive but finding the right person to change them is.:Confused:

checked the battery it seems like it was installed on Oct 2014 and states on battery 3 years warranty. It was changed by last owner.

There's a Garage in London that M-A8 loves.
I can't remember their name but they always do alright by him.

I would have the battery tested first, most motor factors will do this for free, could be a dead cell.
An OEM spec Bosch, Vartra etc. would normally last around 5 years but it could be a cheapo replacement.
If you have 5 working glowplugs, a 3.0TDI will start fine even in cold weather, my old 2004 D3 had a duff plug for the last 2 years I had it. Plug was stuck and I was advised to leave it as it's a head off job if it snaps.

Thanks. Yes I think mine has one duff plug as well. It is the same garage I took it to as per my friend Marcin recommended. They are top and it was one of the mechanics who said leave it. Will check with battery first me thinks and then take it from there. Battery still under warranty but will need to find the paperwork:Confused:

If you cant find, the paperwork, the sale date is often stamped onto the casing for warranty purposes. You then just need to find somebody who sells that brand of battery. Obviously much easier if the receipt can be found.