You will find the training hand a valuable tool while you are learning and years down the line,
once you think you know it all, something new will come along that you will want to try out, whether its a technique or design, and the hand will be so useful for practising this on,
the essential nails one and creatives one are the same hand, i would not bother with the cheap £10 one.
No you would not be able to teach yourself Brisa as it works totally different to the L&P and you would not be insured to use it on paying clients without the training first,
the minx you could possibly learn by yourself but it would take time to get them perfect,
nails is a life long learning cycle and you need to be prepared for this,
none of us do the foundation and that is it, we have geeks on here that have been doing nails for over 20 years but they still take classes to keep up to date with things,
if you are serious about nails then you have to take the education seriously too,
you have made a great start into the industry by choosing the best to train with so keep it up