The H/S 300 (ideally a 'C') is the perfect trainer - safe, fun, well engineered, intuitive, nice handling, plenty of power, etc.
The throttle shouldn't be a problem as it has a correlator. So you set the throttle position and it automatically adjusts as you raise or lower the collective. You might want to make the occasional tiny manual adjustment, but most of the time it does it for you.
If you are doing more than 100 hours pa then I reckon it becomes viable to buy. Then it's your helicopter, its available when and where you want it, you have a more intimate relationship with it, and you'll probably learn more quickly. And,
you own it.
You should get a nice 300C or newer Cbi for around a £100k. But the Enstroms are also excellent helicopters and this 280FX looks very good value
Enstrom 280 FX