I have just.purchased a 2018 Fiesta Zetec Auto running on Bridgestone tyres and am disappointed with the amount of road noise,could this be just the choice of tyres?

Have you checked your tyre pressures? And yes, the tyre brand and model definitely affect the amount of noise. Also the bigger rims you have the less thinner profile tyres you have which can also affect the road noise. I have 15" alloys with my winter tyres and 16" with my summer tyres.

Yes, as above, I have found differences in tyre noise when swapping between brands. Noise can also increase as the tyres wear. 

Another factor is road surface. The authorities round my way make extensive use of "surface dressing" (spray wet tar and throw chippings over it) which is very noisy and causes a lot of stone chips as they never roll it or sweep up the debris. When I (very rarely) find a section of properly surfaced smooth tarmac the difference is amazing!