I find the problem is that the Spitfire fliers tend to hang out over Dover at very low level. This makes them hard to spot if you are in a 109. They don't venture over the water as they'll get seen pretty quickly.
When you finally spot one and dive down you'll discover they are all down at that altitude, it gets a little dangerous as you can get too involved with one and easily get another on your tail. Now you can limit it to B&Z slashing attacks but you'll often lose them in the ground clutter so you do have to T&B slightly and that's when the other Spits get involved with you.
On the other hand if you are a Spit it's easier, you just take off and look for the flak puffs in the sky, there's your enemy. Give him a little squiz of 303's and he's got a small chance at getting home, on the other hand if he hits you, just do an emergency landing and don't worry about finding a place to do this as trees don't exist.....