Swap wunda 91.713 thermostat with nest E wiring UK

Hello guys. was hoping to get some help with the wiring installation as the nest installation instructions are absolutely futile.

I have a nest gen 1 controlling hw, boiler and radiators throughout my house and a wunda thermostat controlling the wet ufh in a separate zone. to install the heat link, i need to know which of my existing wires go into the nest e and the nest instructions does not tell me that. see photo below.

many thanks for your help guys.

https://www.diynot.com/diy/media/albums/wunda-thermostat.27099/

Existing L into Com on nest E
Black wire in L1 to NO on nest E
safely isolate and tuck away the N it isnt used on the nest E

thanks Ian, ive wired it up but the floor is too warm to test now. will give it a go tomorrow. fingers crossed! thanks again

its working, cheer Ian.