Unless you have any desire to switch careers (i.e. Actually quite fancy the idea of being a Teaching Assistant), then opt for TUPE.

There are horror / scare stories out there about TUPE, but in theory it can be a positive move if you are good and prove it to the company.

At the moment I guess you work in a school and have limited scope and progression. You might be a tech and then become an assistant network manager / network manager, but what then? Do you learn anything? Can you actually get anything better than that?

With TUPE the company will essentially be investing in you furing the initial first year (or however long is written in the contract!) If you prove your worth (like you would with any new employer) then it's in their interests to keep you and reward you.

I'm not in exactly the same situation, but have been in a similar one enough to actively read up (a massive amount of) information on it. I'd certainly see it as a new challenge and a positive step.