@JATPHOME 

You may wish to research for ways to bring Ethernet cable from modem in the front and to the back of the building, or if you have TV cable going from front to the back of building - it can be used to transfer Ethernet, with MoCA adapters.

If this is not the option, run the following test: have good quality WiFi router connected to the modem. Walk to the middle of that 35 meters distance, so that you are approximately 17 meters from the building front and 17 meters from the bulding other side. Using smartphone or laptop, check quality of signal between this point and WiFi router. If quality of signal is poor, TP-Link Deco may not be the right choice. See How to check the associated/link speed on a wireless client

If quality of signal is good, you may be able to get WiFi from modem to the end of the building by getting 3-unit Deco mesh, placing one unit with modem, second in the middle and third close to the end of the building. 

From all available Deco models, and there are many, choose one of the following: Deco M9 Plus, Deco X68 or Deco X90. You should be able to get either of them in 3-pack. 

Because, in such setup as yours only practical test can tell if you can get WiFi speeds that are satisfactory for your needs, buy Deco from the place with good and easy return policy.