nest 3rd generation

I posted this in the central heating and plumbing forum but someone suggested I post here. I am new to this site so please be gentle! I have just purchased a 3rd generation Nest and need to install to the following set up: • Vaillant ecoTech Plus 428 boiler • Drayton LP522 Programmer (pic 1) •...

I wonder if anyone would have time to look at my particular Nest installation query - any help would be hugely appreciated. I would class myself as a pretty good diy'er but I am worried that one slip could fry my boiler. I have just purchased a 3rd generation Nest and need to install to the...