What's it like over here.

I was thinking of upgrading to 500 mbit fibre and my current ISP is Andrews and Arnold is too pricey for me even with a 1tb limit. I have 2 lines fibre and DSL/Phone with TTB. I don't want the DSL/Phone touched and to remain in place for now.

What's involved with switching to IDNet as I am on a 1 month contract with AA and would they be able to change my AA fibre over without affecting my other line. Do Openreach need to be involved as I am on BTw as last engineer tried to disconnect copper and I got him to reconnect.

Any ideas?

It shouldn't affect your second line if you want to migrate from the A&A fibre. Depending on if you are using Openreach or an alt net like CityFibre you might not even need an engineer visit.
I just put my order in the other week to start my switch to IDNet. With OTS it asks you questions about your existing ISP and it will tell you if it's found a match on the database. It was relatively straight forward.

No guarantees, but transferring a service on one line should not affect a separate line. You have done the hard part, getting a new line installed where the default would be to cease the original