Replacing the stock radio/tape player in a 2003 mk1 Yaris

[SPOOKYJIM]

I'm looking to fit an aftermarket head unit into my 2003 yaris but it doesn't look like something I'd just be able to swap out the factory one by unclipping it and sliding it out. 

How would I go about fitting an aftermarket one?

I was planning on just fitting a single din head unit so I can mainly have bluetooth ECT.

I've found this fascia https://www.dynamicsounds.co.uk/connects2-ct24ty06-toyota-yaris-car-cd-stereo-fascia-panel.html

Would this work with my yaris? And what else would I need to fit a new head unit?

I'm trying to avoid cutting up bits of the dash if possible but if that's the only solution I don't mind spending a bit of time trying to make it look as nice as I can 

[Cyker]

Traditionally, people leave the integrated headunit of the Mk1 Yaris alone and fit the aftermarket stereo in the single-DIN-sized slot (Which can be removed) underneath it.

This is much easier than trying to swap out the integrated headunit, and then you just need to get the various ISO conversion wiring harnesses, and things like the widget to convert the steering wheel controls into ones recognised by the new headunit.

2Connects is a good place to find most of that stuff, although I think Halfords also sell a lot of the wiring harnesses needed too.