Would probably be going with a managed limited company as I have little financial/tax knowledge and would prefer to concentrate on what I’m good at.
That’s what an accountant is for. Anyway, setting up and running a Ltd. company is a doddle, there’s a bit of paperwork to keep on top of but nothing remotely difficult. I went from ‘thinking about a contract position’ through ‘reading up about contracting’ to ‘setting up a Ltd company and having an accountant’ in about four days. It’s really not that hard, loads of online resources (Contractor UK being one of the best ones)
As for accountants, I use and would recommend SJD, they’re online and have quite a few local offices.
As for getting sponsored through clearance, any positions that I’ve seen that needed clearance expected you to have it already. I would think that would especially apply to contract stuff, where they’ll expect a quick start. Could be talking out of hat though, I have no specific experience in the field, I’m more a financial services BA/SA.
Go for it, I’m glad I did.