For poppyeye, I'd just like to say don't give up so easily. There isn't much "advice" I can give as I'm not aware of your reasons for wanting to do a teaching course, but when I did my part time CELTA (3-4 months), I was working Mon - Fri, 9-5pm, whilst cramming in my CELTA at the same time. It was tough, and I admit there were times when I felt like I should just pack it in.
But I kept going, but only because my personal reasons were that I had become disillusioned with my 9-5pm job, and wanted to go back to Hong Kong to see what my parent's culture was like.
The CELTA is tough...but bear in mind that you actually carry on learning as a English Teacher when you get your first job and start having to juggle lessons on a near daily basis. I have 1 day off a week and usually spend my day off in the library, finding books to read to my play groups or teaching books to gain some more fun exciting games for my students.
I don't want to lie to you. To actually teach English isn't impossible. To actually teach English well, and get the students to enjoy English at the same time is difficult...especially trying to enjoy it at the same time.
...but when you spend 4-6 weeks teaching 3 year olds how to speak English, and they start singing English songs and responding to simple questions like "How are you?"...it does bring a smile to my face and it makes my job all the worthwhile.
Good luck with whatever you decide!