c4 Coupé battery removal

[moizeau]

I need to trickle charge the battery on my c4 ready to finally start using it. The battery was OK 3 or 4 weeks ago, but with the cold spell it's dead. It's sat on the drive for 16 months surplus to requirements, just getting started and whipped down the lane from time to time.
How many things do I need to remove to get battery off to charge it? I'm guessing air filter, anything else, it's half buried underneath the windscreen? It's a 2005 2l 136 petrol.
Cheers