Hi there.
Any of these Awarding Bodies are acceptable - NCFE, CACHE, City & Guilds and EDEXCEL.
It used to be the case that schools would take on those without any experience and whilst this still does happen, it's quite rare. You could perhaps volunteer in another role (dinner lady etc) and move across to a TA if one becomes available.
Gove has said he won't get rid of TAs. However, the Department of Education has cut funding to Local Education Authorities and is trying to broaden the role of teachers to incorporate TA duties. It's really down to the LEA to decide whether they need TAs for their schools and many of them recognise the need for TAs. Ask any teacher and they'll tell you how important TA roles are (the trade union, UNISON, completed a survey end of last year which demonstrated why school leaders value TAs - read it here). Ultimately it really depends on the number of students that need help (statemented students) in a given area.
If you're unsure, contact your LEA and ask them what the requirements are for TAs. Usually they'll say Level 2 or Level 3 etc. There are no formal qualifications for TAs, but there are 'suitable' ones. You can see a list of the most popular ones here - TA course comparison
There are also SEN specific courses, which may help if you want to work in a special needs school(?)
If you do decide to pursue an online QCF (formerly NVQ) course, opt for the Certificate or Diploma, which will require a work placement (you can organise voluntary work in your local schools for this). If you can't arrange some form of work experience, the Award will suffice as this includes less units and doesn't require work experience. As others have said, work experience is key so I would only opt for the Award if the others are unattainable.
The courses will have different names, but it's the qualification at the end which is the important part. Again, check with your LEA about qualifications they'll accept.
Higher learning courses (Open University etc) are very good, too, and can certainly help improve your prospects.
If you have trouble funding your course, you may be able to receive a grant to pay for it. Have a look here (enter a few details to see which grants are available in your area) - grants-search.turn2us.org.uk
Best of luck and don't let the Job Centre get you down.
J