Welcome!
If in doubt, buy a machine one size larger than you think that you need. You find other things to do as you become more used to the machining. If you think that a SC3 is what you need, can the budget expand to a SC4? The larger machine will do the same jobs, and extra ones also.
Squeezing a lathe and a mill into 1.7 metres will need a large shoehorn. For me that would suffice for a small lathe, but not both. £600 may get you something like a SC3, but a mill for £300 sounds pretty small.
And don't forget to make allowance for buying tooling and accessories!.
I managed without a Mill for a few years. If push comes to shove, You can mill in a lathe without a Vertical Slide.
(Some can be a bit flexible, IF it can be fitted to the lathe ) Holding the job in the Toolpost, (or on the Cross Slide ) and an End Mill in the chuck may be a more rigid way of doing the work.
For screwcutting, I would have making a Mandrel Handle as one of my earliest priorities.
Sensibly, you would not use Taps or Dies under power. (I do, but use the "jog" facility of the VFD, and can still get bit wrong, which you are unlikely to have ) Low speed may risk overheating the motor, and it will not stop instantly, so the Tap or Die could hit the end and either strip the new thread or break and scrap the job.
Rotating the lathe by hand keeps the speed low, and you can feel the torque being applied, with the ability for an instant stop.
Better to start by making some accessories such a a Mandrel Handle, and Centre Height Gauge, than rushing into things and possibly wasting material and time having disasters.
Howard
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