I'd also reccomend easyJet. The pay is much better than Excel, and the company has a really relaxed and friendly feel. You work hard but it is rewarding.
Tips;
Smile lots.
Get involved with discussions and planning tasks.
Give lots of eye contact and attention to whoever is speaking.
Have a laugh and relax. Then your personality will come out.
Lastly:- Think of times where you have used your customer service skills - eg dealt with a crisis/ gave someone support / gone the extra mile etc...
Good luck.