Upgrading fence for back garden, do I need permission?

Hey,

So my back garden fence is a bit shite, I live on the end house in an estate and as a result the back garden fence is next to a public path that leads into other estates.

The fence is probably just under 2m if you are standing on the side of the path. But my garden is sloped, so if I'm standing on my decking, I can easily see over my fence, so if in the summer I'm cooking some sausages on the BBQ, I can make eye contact with everyone who walks by my house! It's kinda annoying tbh, as we're all nosey bastards so we all just stare at each other for a brief moment, helpless to our own noseyness lol (no i don't offer them a sausage!!!!!)

I want to build a bigger fence to prevent this! To better picture this, think of me standing where my back door is. The path I'm referring to is actually lower down than the property level, which kinda sucks for privacy purposes. Would I need to apply for permission to build a high enough fence to protect us from our communities eyeballs?