Can't think of a better time to get the Ordinary foundations since ASOS currently has 14-15 shades out of the full 21 shade range in stock and there's 30% off. I've been waiting for months for the Ordinary foundations to come to Australia but there is still no E.T.A. The waitlist was 25,000 long before launch and it goes in and out of stock from various US and UK retailers including the official site.
They come in yellow to pink tones from light to dark. Choose coverage foundation for full coverage and serum foundation for light to medium coverage. The shade guide on the official site may be helpful. If you know your MAC shade, this is MAC to The Ordinary table is useful. You can also just buy the coverage foundation (if your shade is in stock), then mix in some serum if you feel like going lighter coverage on certain days - this trick works well.
For retinols I've used their 2% retinoid which is a retinol derivative with no irritation compared to retinol. Their high quality rosehip oil is also excellent for skin health and balances out oily/combo skin.
I've raved about The Ordinary in other deals, plenty of information online including youtube reviews. Here's a youtube review from Wayne Goss.
You'll need to spend minimum £20 for free shipping. Original 30% off deal
I purchased both types of The Ordinary foundation a while back from ASOS and have to say not impressed at all. There do seem to be a lot who love it though.