Unless your qualifications where in the last two years I don't think you'll get in by exemption however as you have qualifications already in accounting you should be able to do home learning fairly quickly to get your ICB qualifications and Practice Licence.
Yes there is work out there and a fair amount of it can be done from home ( I presume your happy to pick up the paprework from clients). You do need to be prepared to get out and network as it will take a while to build your client base.
You ask why do ICB. There are similar professional bodies so it depends which you go for but I think having a professional body behind you is an advantage.
Good luck if you do decide to join us.