Switching from BT with OneTel CPS

[#1]

I rent my landline from BT and have Carrier Pre-Select with One.Tel (aka TalkTalk), but want to transfer the whole caboodle to PlusNet.
I know that PN completely handle the transfer of the line from BT (subject of several other posts on this forum!), but do I have to do anything special to disable the CPS agreement with OneTel or do you think this will just lapse automatically?
And yes I've seen the direct debit cancelling advice already.

[#2]

Hi there,
As the CPS is a 3rd party agreement you would need to contact Talk Talk directly and end your agreement.
When you move your service to us your existing phone line provider (BT in your case) would be notified automatically.

[#3]

Thanks Mand, that's very helpful.