Welcome to the Forum
Before yoepu buy either a Lathe or a Mill, have you decided mwhat you are going to produce on them?
You will have difficulty making a 7 1/4″ gauge loco using a C1 or Peatol sized lathe, but equally, a machine capable of swinging 12″ is not ideal if you want to Make watches or small clocks.
You can do small work on a big lathe, butb the reverse is much more taxing!
By all means, buy a machine that seems a little larger than you at first think that you need, but don’t go OTT.
The motto has to be “Horses for courses”.
Find and join a local Model Engineering Club.
Members may let you see their machines, even use them, and help you decide what you need.
A friend had a go on my 12″ swing lathe, but he bought a C1 for his O Gauge model railway work
A new machine will have the advantage of a warranty and technical back up in case of problems, but might need some fine tuning for optimal operatiom.
A secondhand machine may have been looked after, but equally well may have wear, or might have been abused. If you are unsure rake someone knowledgeable with you to check the machine. Preferably, try it out.
Whatever you buy, it will have backlash, and being a hobby machine, do not expect the precision of a toolroom machine costing twenty times as much.
Excellent work can be made on a hobby machine, but more care and skill is required.
Good Luck with your search!
Howard