As others have said, diet is key.
Download the my fitness app, it's great for letting you see just how much you consume..you type in the product and it gives you the breakdown split protein / fat / carbs.
Gyms are all very well but it's finding the time to do it..especially after a long day in the office.
I too bought a kettlebell (8kg) and use this at home as well as doing some skipping..5 x 3 min rounds.
The advantage of this is you can do 15 mins each night and that is all it takes..no 20 mon drive to gym , workout, 20 min drive back etc..it's a lot easier to stick to it because of that
Good luck!