Hi,
First of all, welcome to the sickness, sorry, hobby.
Second, Spitfires are nice to fly once in the air, they tend to try and tip onto their nose when taxing and taking off. So take it very easy with the throttle while on the round.
If the model is slightly heavy then increase your landing speed a little. You don't want to land a Spit slowly anywhy, they do like to tip stall and drop a wing if you slow them down.
A built up wing should be lighter than a foam wing so I would check the condition of the wing you have and finish the model if it looks ok.

Enjoy.