How do I swap this shower mixer tap ?

[tangerine0072000]

Hi all,
My shower mixer tap has seezed up and I want to get it swaped out, but never done it. Wondered if it was something I can do or whether I should get a plumber out.

Originally (before any tap was installed) there were two copper pipes comming out of the firewal about an inch.

This Triton mixer looks as though it is just held on with two big nuts. Is it just a simple matter of undoing the nuts?

Please see image of my mixer tap below below.

thanks

 

[stem]

The pipes are connected with the "big nuts" but these type of mixers generally also have a bracket behind the mixer that it is locked on to by a fixing screw of some type.