There is absolutely no problem obtaining spares for Colchester lathes.
The Student has a 40mm bore spindle, the Chipmaster 35mm. Bantam 2000 is 32mm . Colt is 35mm .
Myfords only sell because it is what model engineers use , and what model engineers buy. They buy them as a result of Myford marketing without reference to how good or bad they actually are. Myford sell them as the only lathe for a model engineer, and there are books and articles about them everywhere. I fail to understand why a model engineer should make this choice since as pointed out the spindle bore prevents entering much work. If you flood the market with adverts for the Myford then you start to get sales, however bad the lathe actually is.
If you are determined to own a Myford, then there is the Myford super 7 plus "Big bore" that had an inch bore spindle instead of the tiny 3/4" bore, but in my opinion you are seriously low on specification , even then.
I ran Model Engineering Classes at two different colleges, and many of my students has Myfords, but came to our courses to use the Colchesters and the Harrisons because they where out of capacity on the Myford and a bigger lathe was needed. Hardly any of my students could have completed their models if they had not got access to something bigger than a Myford.