Hi assuming tdi? I did all this myself with a pro mobile AC man to de gas regas and leak test. He did a de gas then came back next week. Worked well.
Anyway, basically its a doddle if you dont mind taking the time to jack up, wheels off, arches out, bumper off, then its straight forward then. Just removed the intercooler and there she is. The bolts for the pipes are torx and do be gentle with them! Its wise to replace the seals/orings on the two pipes and also to add 20g of PAG oil to the compressor if the new one doesnt come with it prefilled (important!) I would add a bit to a second hand one for good measure. Theres a maximum for the system, memeory signals 120g at me but do some googling its all there, somewhere.
The AUX belt is a 16mm spanner or slim socket to push tensioner arm back to release the belt, then mark its direction, amke sure it goes back on the same way.
Have a look at the top of the compressor theres a oblong lid, if 2nd hand check this doesnt leak when fitted using soapy water (bubbles = leak). this lid is bolted down and underneath is a rubber gasket. When I did mine the lid leaked so I refitted the old one and luckily it worked. Sounds complex but I was unlucky. You can get a AC sealant gel to rub around the gasket for good measure, my mobile AC man did this for me and it worked well. Never had such a cold system with 4C at the vents!
I paid £25 for the polo compressor, I actually bought two just incase!