02 sensors galore + secondary air pump (?) W12

[Chin]

When I got the car it needed a sensor 1 bank 1 02 sensor replacing so I replaced it and cleared the fault, I also ran a whole bottle of cataclean and all was well, until today I had the car scanned and now sensor 1 bank 2 has gone **** up I don't know how hot the engine should feel after a spirited drive because Ive never had a car with such a big and powerful engine but there is quiet a bit of heat coming out of it, also ive noticed that theres a slight "noise" coming from the front drivers side arch , is that where the secondary air pump is ? its not a rattle or squeak but sounds more like tapping , not overly loud you can just hear it if you bend over to listen to it. Is this normal ?

Now the car is still under warranty but a) id have to take a day off work and loose out on £££ and b) it would cost me at least £100 in fuel to drive to warrington and back so I would rather pay someone £250 max to replace the sensor for me as AFAIK id need to get the manifold off to get to it and I don't really fancy doing that , not on a W12 anyway

Is taking the engine out REALLY necessary to get rid of the b@stard cats ?

I know im a pain in the back but im all new to this big petrol engine malarkey