Hi Claire,
Greetings from Melbourne, Australia.
I have been doing some freelance BA work over the last year for smaller companies. The type of work which has come up for me is the documentation of business processes (for a company that was looking to standardise their approach to software development projects), and requirements elicitation for small/medium web systems/projects.
Some of the challenges I have encountered are around the project management side of things - unlike in a more corporate type of environment on a big project where the BA work is fairly well defined and there is a PM keeping things moving along, in smaller companies there sometimes isn't anyone else performing that role. So it can be hard to get time from all the stakeholders so as to stick to schedules etc.
If you are working on technology projects, smaller companies often don't have inhouse developers. So I have found myself having to get quite involved in procuring and managing those technical resources simply because there hasn't been anyone better placed to do so.
The other comment I would make is around the effort required to keep up with time sheeting, invoicing, chasing payments etc. If you don't keep on top of it it can really sneak up on you and become a bit of a burden. Again, not the kind of thing that you need to worry about when working for a corporate, or even on a fixed term contract where you are being paid on a weekly basis as opposed for the specific hours you work. If you are planning on freelancing and don't already have systems set up for bookkeeping etc, and if have time on your hands at the moment before the projects start to roll in, then I would recommend getting that stuff sorted. I use a product called Saasu for my books which I would recommend, and is free for less than 20 transactions per month. There may be more suitable local products. I also used a product called Tick (www.tickspot.com) for time tracking which was great.
All the best with your endeavours!
Cheers,
pete