HI, and welcome!
You can get interior ones that take power from the head unit to amplifiy the signal and attach themselves to the inside of the windscreen. Might be worth a look in your local Halfrauds.
If you are removing the old one you will need to get at it thru the wheel arch, or you can always leave it there as you will just have to unplug the co-ax lead when you fit the new one.