I'm planing to buy a cheap computer, and was wondering if it would be enough

Being in the US, I don't know what 200 pounds would buy you, but $200 US dollars won't buy much. $500 US dollars can get something decent.

Fortunately for us, web developing doesn't require a super powerful computer. Code itself doesn't take much room on a hard drive, it's not hard for even the entry level cpu's to keep up. Ram can be important if you're like me have a whole bunch of tabs and things running at once.

All of that sounded great until you said edit videos. That's a whole nother world, and you do need a pretty powerful computer to pull your hair out trying to do so. Even new $500 US dollar computers would/could struggle editing and rendering video footage. Yes, while hardware gets cheaper/better, video resolution continues to skyrocket, creating a cat and mouse game. It becomes "ohh sweet, your 4 core cpu can process 1440p video no problem? Sweet, let's make 4K mainstream and see how long to you pay up for a 6 core cpu."

Again, not knowing what you can buy, but knowing what you want to buy, I'd recommend no less than a 4 core cpu, and as much ram, and hard drive space as you can afford. I'd max your budget. If you can drop the video editing, you can save money by dropping down to a 2 core cpu, and less hard drive space.

Apple computers are, in my opinion, losing their justification for me. Their hardware specs are terrible, while their prices have skyrocketed. The latest rounds of macbook pros that came out are anything but professional grade hardware, and have left me wanting a whole lot more. If you want a great computer for development, you can build a nice, simple computer and install linux on it, and have a great development environment.

I picked this one up about three months ago for less then $300 (It looks like $249 comes out to 205 pounds at current exchange rates). It's certainly not top of the line and in fact is a couple of generations old. The plus side of it is that upgrades are incredibly easy, two clips allow you to slide off the back cover and get access to the CPU, memory and hard drive. Unlike most laptops the CPU is socketed so is upgradeable to and i7.

I immediately ditched the windows that was preinstalled and formatted and installed Linux Mint. I do all my Treehouse curriculum, as well as image editing on it (and obviously mindlessly surfing forums!) I also use it for editing videos for my daughter's youtube channel. Nothing fancy in any of that, but it performs flawlessly (other then mint occasionally not finding my wifi router and needing to be rebooted) with the factory hardware.

So yes, you can definitely get by with a 200 pound machine, but I would strongly recommend being mindful of ease of upgradabilty for anything you might want to do down the road.