Scotland, so you can see shit like this:
^Old Man of Storr, Isle of Skye
^Eilean Donan Castle
^Portree, Isle of Skye
^Edinburgh Castle
^Cairngorms National Park
^Ben Nevis
obviously i'm biased, but really no matter where you go you'll have an amazing time. England and Ireland are both beautiful countries as well, and really if i were you i would just go to them all haha
certainly don't base your opinion off london. it isn't like anywhere else i've been in the UK, and in my opinion the vast majority of the stuff here to see is outside of the cities.
Edinburgh is a great place to start in scotland since it is so old and historic, and i mean, it has a castle right in the middle of it, which is pretty fucking cool. the Isle of Skye, off the west coast of Scotland is absolutely mind-blowingly beautiful, and has so much on offer, especially if you enjoy photography like yourself, and if you like seafood, you'll be in heaven. the highlands are also mind-blowing, and if there's snow you can go skiing, or else hit up the various dryslopes around the country. Glasgow is great for shopping but for some reason it's never appealed to me anywhere near as much as Edinburgh.
I dont know England terribly well, but the scenery in the north and around the Lake District is amazing, and down near Cambridge and Oxford is really nice too.
Ireland is also great. you wanna go to Belfast, Dublin, then head over to the west for some stunning scenery.
other than that im not sure what to suggest that hasn't already been said, but i know for sure you'd have a great time in scotland, and if thats where your family is from it'd be great to see it for real