Hi Ian,
i have been consulting for 4 years now, and I agree with all the comments. I initially started under an umbrella company which is by far the easiest way you do give them a small %. After a couple of years I then moved to ltd. I have been fortunate with a large network I have been able to source my own work. I have colleagues who work the management consultancies and all I would say is they own you. They have been sent to place at short notice for short contracts, of course you don't have to worry about sourcing work and if you need income then it ticks that box but work life balance goes completely out the window.
Sometimes a quick browse of job adverts and a cover letter offering an interim solution can work well. Alternatively I'm not sure what sort of project management you have but speaking to vendors of potential products can help to almost offer a "supply teacher" or short term solution to their resourcing needs.
Good luck