How will starting a company (uk ltd) affect my credit score? Will it be negative?
The business itself will not effect your credit score but as a start-up you as a director will probably need to personally guarantee any borrowings or finances. A bank will run credit checks against you as the personal guarantor and this will appear on your credit file.
Wile not damaging it can in some small way affect your rating.
A UK plc is nothing to do with any individual's credit score.
Bear in mind that starting and running a plc requires a lot of paperwork, compared to a UK ltd.
What makes you thing a plc is the way to go?