Pre-DVT, I hardly used my laptop. I would sit at my desk and use my tower PC with its 24" monitor.
Once the clots had damaged the veins in my left leg though I found that I could no longer sit at a desk or table for long. I can sit at a dining table just long enough to eat, but then I have to get up and move because my leg starts to get really swollen.
As a result of this I have been using laptops for the past 9 years. Fortunately, I am perfectly comfortable sitting on a sofa with my legs up on a footrest. I have the laptop on a laptop tray. The screen is only a fraction of the size of my old monitor, but I am sitting much closer to it and it is much better quality, so that's good.
I use my phone or a tablet in bed but much prefer typing on a proper keyboard and looking at a bigger screen.
There will be probably be someone at your local market or phone shop selling them for a few pounds!