You definitely need in-depth feedback on your essays to help you to improve. That's kind of my job - I run a feedback and editing service, but I don't really know that I'm meant to tell you that on this forum? Sorry if that's the case, I wasn't intentionally coming here to tell you I edit and help people learn to write essays. Anyway, your teacher might be willing to help students improve their writing over the Christmas break - it can't hurt to ask, right? Also, if there's someone in your family who is good at writing (and who is willing to give constructive criticism) you could ask them to help. There is absolutely no point practicing writing essays if you don't know what you're doing because you can just end up reinforcing bad habits. I agree that it helps to read good essays (but again, you need to be able to tell what a good essay is).
Oh, and Williamhuff - those essay writing services are not going to help someone learn to write essays - having someone do your work for you (especially when it's from America or some other country with a completely different education system and different rules about essay structure, grammar and punctuation) is never a good idea. You need to be able to learn to write good essays yourself, and that happens by practicing and improving your own.