HS2 are consulting on a report on the environmental impact caused by the link following the Overground route between HS1 (on York Way near St Pancras station) and where it joins the mainline near to Adelaide Road.
They will be working for a period of seven years, starting in 2017, altering or rebuilding all the bridges and adding track to the viaducts
The main depot is on Camley Street at the foot of the Agar-Camley Link, another depot is at junction of Royal College Street and Camden Road.

See http://assets.dft.gov.uk/hs2-environmental-statement/volume-2/Volume_2_CFA2_Camden_Town_HS1_Link.pdf

I will put a draft response in a thread related to this issue. Feedback will be welcome. You could also consider replying to:

HS2PhaseOneBillES@dialoguebydesign.com

FREEPOST RTEC-AJUT-GGHH
HS2 Phase One Bill Environmental Statement
PO Box 70178
London
WC1A 9HS.