I'm a TA and I agree it's not about displays anymore and all about targets and moving on children's learning. At my school TAs are being cut back and the remaining ones have to really earn their pittance, you have to love it! Luckily I do 
We are constantly being observed and assessed, our Head is particularly keen on a surprise drop in and feedback can be brutal, I've heard.
It makes me smile wearily when people assume we just sit around cutting and sticking and putting on plasters (we have a First Aider for that).
We have an ex High school teacher working as a TA currently, management absolutely love her! [wry smile]
You will generally be there to support a specific statemented child. That could be for ASD or ADHD or developmental delays (they are the most common). You will work very closely with the SENCO to set targets and keep the IEPs up to date.
There are big changes afoot within SEN so maybe google the changes and show a bit of knowledge about this.
Under the new rules, SEN statements and learning difficulty assessments (LDAs) will be replaced with education, health and care (EHC) plans taking children and young people up to the age of 25. From September, new assessments of SEN will follow the new rules, and support will be provided through an EHC plan.
School Action and School Action Plus to end
School Action and School Action Plus – intervention schemes that tracked progress – have been removed in the draft code. Instead, there'll be a single school-based category for children who need extra specialist support. You should set out interventions and expected outcomes for these pupils, and review progress each term. You must also inform parents when pupils without an EHC plan receive special support.
I have a dd with AS so I see things from all sides which helps me (and sometimes hinders me)