You should know how to change your own brake pads.. so yes, get the kit and have a go.
Make sure you always jack the car up using the proper jacking point. Put a small block of wood inside the jacking cup on the jack, to prevent damaging the jacking point. If you don't have any wood, use a folded up piece of cardboard.
Don't work on the car with it just on the jack. Once you have it up in the air, plonk it down onto an axle stand.
If you're on tarmac and it's a hot day, place a sheet of plyboard or similar under the axle stand to stop it sinking into the tarmac.
1) Loosen the initial stiction/tightness of the wheel bolts.
2) Jack the car up
3) Lower it carefully onto axle stand(s) placed under the car .. I'm not sure where to place these on a GTV.. someone will tell you.. but usually under the wishbone mounts is the kiddie (again, use some cardboard or a rag between the axle stand and the car to prevent damage).
4) Remove the wheel bolts and the wheel.. and then you can get on with the brakes.
As a tip, you should loosen the brake fluid reservoir cap, since it makes winding the pistons back a lot easier.
Also, if the brake fluid level is high to start with, take some out using a syringe or just a clean cloth (let it soak up the brake fluid).
Brake fluid will melt your paint, so keep any drips or spills under control. Mop them up with water and then dry them immediately.
You know to use copper grease on the back of the pad where it contacts the piston and also in the caliper slots...
If the new pads are a little tight, you can clean up the slots with a file. If really necessary, file away the paint on the pads where they fit into the slots. The pads should fit with some movement.. they have to be able to slide backwards and forwards.
As a final tip.. nothing should be difficult or tight or held in under pressure. Imagine that Luigi assembles those things in 5 minutes.. so if you're beating or hammering it for hours.. something's wrong. Take a photo of everything before you dismantle it, so you can be sure you put the new one in the same way.
Clean off any fingerprints or grease from the discs. Use Electrical Contact cleaner (or Brake Cleaner..
).. NOT WD40.
When you have the car on the ground again, PUMP the pedal several times before you even start the car. The pads may be tight against the pad or they may not. The pumping brings them into the engaged position.
Double-check that the cap is back on the master cylinder / reseorvoir.
Drive the first few laps of the ring road carefully so the new pads can get used to their new location. You can bed in the pads by carrying out several hard stops from progressively higher speed in quick succession. That makes the new pad material clean the disc and deposit some of itself onto them instead.
Don't charge into a bend at full speed and then try to use the brakes in anger for the first time... (unless there is a big field the other side of the hedge). You'll hurt yourself..
But it's not so bad.. just take it logically and carefully and you'll be fine.
You could bleed the brakes too while you're at it... but it's not strictly necessary if this sounds like too much to consider already.. Do it next weekend instead.