Ah ok thanks for your response. So if the actual product was realised after leaving the employer (or officially) that's what would be considered the IP, even if the product name was established whilst employed? My plan is to perform all the research around the periphery of my idea and start the actual build (based on several PoCs) when free of my obligation to my employer (i.e. have left).

I agree buying the domain name is little effort whilst it's available. Seeking the services of a domain broker is not so easy if the domain is squatted on by procrastinating.