I want to put a mk6 golf dashboard into an Audi a3 8p they are the same platform I’m just wondering if it will fit and what I would need to do to make it fit 

From what I've read from people who have done this on older a3s, you're best getting a golf dash from a car the exact build year as your A3. 

Then In theory it'll fit as mounting points should be the same, not sure how it'll work with the door cards though? 

Ie any protrusions from one or the other that'd stop the door closing. 

Don't forget that the instrument cluster is coded to your car with the imobiliser so ideally you need to keep the same cluster.