I took the plunge and bought a double DIN unit, and a facia adaptor, which to me appears warped! Is it meant to be so bent? Car goes to a local repair man tomorrow, whom I don't know, so maybe taking a risk...
In the end, being a poor pensioner, I went for a cheap option -
https://www.ebay.co.uk/itm/Android-8...72.m2749.l2649
Even though I surely know generally you get what you pay for...I still bought it!
I'll let you know how it turns out...