Faulty reverse switch wheel arch or battery

Hi Guys
My reverse sensors became intermittent then stopped completely and the rear wiper doesn't come on automatically but works if I turn them on manually and my reverse lights have gone too. After a bit of research and reading old threads I've concluded my reverse switch has gone.
Will it be easier to take the ns wheel arch for access or battery, tray etc. I've read that the battery tray can be a bugger to get back in?
Grateful for any opinions.
Cheers