I may have 1hr 10min to get from arrivals in terminal 2a to the TLGC station . Is this too close to get through customs etc. Will have just carry on bag
French customs/immigration is usually quite quick. They don't go through the endless discussions with everyone like in Canada / USA. They just scan passports and send you on your way.
The walk from CDG Terminal 2A to the TGV station (located between Terminal 2 C & D wings) should take 5-10 minutes.
I think you should make it.
I assume you've purchased your TGV ticket online? This would go a long way in helping you make that connection.