Hi dressmedeadly,
I did Pitmans Legal Secretarial Diploma in 2009. You are supposed to finish it in a year but they do give time extensions. I did my from holborn training in central london. You have to work at your own pace. Every things is recorded and you have to put earphones on and just listen to what is on the tape and follow from there. You are given workbooks. If you get stuck then just stop the tape recording and ask one of the staff for help.
When you are ready then you give your exam. I don't know if the rules have changed but during my time I was allowed to view my exam beforehand and hand it back in if I was not ready to sit them, which was great. So there is really no deadline, but ideally you should not take more than 1 month to finish one course at a time. It really depends how many hours you put in. I would say to you is that start the typing right from the start so that you do alot of practice. If you fail your exam, then I think there is a charge of about £25 for resitting. So it is best to be sure that you are really ready. One thing else is that when you are doing your exams don't be rushed. Take your time. When I did them, I took as much time as I could.
The Pitman diploma's are not cheap. My full diploma cost me about £3,400 in 2009 not to mention the travel cost which accounted for another £800 pounds. In the end I had 9 distinctions and 2 passes. I have heard that they have gone up in price.
The institue of legal secretaries diploma is cheaper. You also get their membership and can register for jobs on their website by uploading your CV. You can also do it by distance learning.There is another one called Souters. Check them out as well. I don't where you live but they are based in central london.
At Pitmans if you don't finish your diploma but the date set out, they then can extend it. It all depends how far you are in the course.
I hope this helps. Any questions then drop me a line.