Apologies for the slow reply again! But I have been doing a bit of digging again and its been really hard to try and find the right combination of motor and gearbox.

So my question is would it be OK to use a 2 speed gearbox and just select the gear i want to use and lock it in place? I mean i cant see why this wouldn't work but there may be something i have missed! Is the method of locking the clutch off the same for example?

The other idea i had was are the gearboxes from say the 12v variant (easier to get hold of you see) strong enough to take the abuse from an 18v motor? Obviously providing the shaft diameter is the same etc.

The only other idea i had would be to maybe get the P60 gearboxes and then buy loads of spare gears etc from them so if something strips i can just replace the gear rather than the whole box? What are your thoughts?

Sorry if these are a bit dumb dumb questions lol but I just want to make sure before i go down a particular route!

Thanks again everyone for being so amazing and patient with an idiot like me!