dose anyone have any tips for changing out an heater matrix i'm a novice at theses things could i do it my self or should i get a garage to do it for me?

 

you can do yourself but its a big job. you have to take the dash out.

 

Yep, dash out. It's not that bad a job though.
If you have air con then that needs to be disconnected at the bulk head in order to get the heater box out.
I took mine out in a couple off hours and put it all back in the next day.