Simon, if your scope comes with the 25mm E-Lux then don't throw it away as its a pretty decent eyepiece as 25mm plossls go, it's sharp, decent eye relief and friendly to use. Best eyepiece I've ever had come with a scope, I still use it occasionally as it's an old friend
Zooms are a question of taste...I prefer a couple of carefully chosen fixed focal lengths. I'd recommend a 8-10mm ortho for higher magnification planetary viewing on better than average nights. You should be able to pick up a very nice one for around $100. Then I'd suggest a 12-14mm for nights that aren't so great, maybe with a little more apparent FOV.