Sounds very like an IR35 type case. HMRC might well still see you as an employee, it all depends on just what contracts your Ltd Co have, and whether these are all with your current employer - in which case you would typically be an employee, not a contractor.
Your contract of employment might have a clause in it to prevent you from working in the same kind of business within a certain radius or within a certain time limit. However, some people conside these clauses to be unenforceable and a restraint of trade.
