I have a job where I work from the office 3/4 weeks and from home for a week. No matter how much I tried to keep myself focused and productive, I found that I just slacked off towards the end of the week. I'm not sure whether this is an appropriate place to post this but I desperately needs methods and tools to keep me in check. Any resources would be helpful/
Work is a "work zone", while home is a "comfort" zone. If you try to do work at home, it is quite likely that you will end up doing "comfort", at the expense of "work".
One of the reasons is that everything at work is designed for you to be as productive as possible, while at home everything is designed to make you comfortable.
If you want to be productive at home, then you need to mimic the workplace at home. I guess that your job is mostly about using a computer. Therefore, create a setup at home similar with the setup at work. Start with the furniture - use proper furniture for work. Do not use the kitchen table. Do not use the sofa. Do not use the coffee table.
The desk should be about 80 cm high, with enough surface area for whatever you need to do. Get a good ergonomic chair, which can be adjusted to your height. DO NOT USE STANDARD KITCHEN CHAIRS OR LIVING ROOM CHAIRS. They will not allow you to get to the "work" mindset.
Ultimately, this is also a problem of "wanting". You actually want to work. Whenever you become aware that you lose focus, get your focus back. Maybe do a short physical exercise - it will help get extra blood (actually, extra oxygen) to your brain.
I have the same problem. Only recently I understood the big problem called "the chair". The kitchen chairs are tall, to help you eat. They are too tall for using the computer. Also, against your desire, the brain associates the kitchen chairs with comfort and well-being, and starts to work accordingly - staying away from work.
As suggested by @JoeStrazzere in a comment, go to work for work. Actually I did it a few times, and some colleagues doing overtime saw me and they were quite shocked to see me in the office doing some personal activity on my personal laptop. But I needed things to be done, and I chose to use the best place I knew at that time.
I think subconsciously, since I know that no one's keeping track/potentially tracking my internet history, I grow lazy.
Actually, somebody, one way or another, keeps track of your work. When working, measure your success by the work you do, not by how much internet you did NOT see.
@Old_Lamplighter: I would only add to it "Dress for work" as well. Don't go to work in jeans and T-shirt, or worse, Pajamas.
My comment: use the clothes that you usually use for going to work, not the clothes in which you are comfortable at home.