Welcome to the forum. We have the 150bhp version of the engine in my Audi A3. My Audi will be lighter than your Golf Estate and I have no problems as regards pulling my 1350kg Eriba Feeling.
The engine is easily up to the job. When towing my 1200kg Triton I typically achieved 34-36 mpg and 40mpg when in NL. With my heavier Feeling I typically achieve 32-34 mpg. I tow in the 50-55mph range, 60mph occasionally.
Your tow bar limit is 75kg, but I would aim for 60-65kg max. With my 75kg limit VW Golf based Touran,Yeti and Audi A3 I have towed 900kg Familia, 1200kg Triton, 1300kg Troll and 1500kg Feeling, All have been best around this 60-65kg nose weight.
Colin