Having lived abroad (and I do miss aspects of it) here is what I do like about the UK...
The friendliness of people in shops and the fact that you can exchange a bit of small talk with the cashier which just brightens up the day (admittedly maybe not true in London), but certainly was not true at all in the other country I lived.
The tap water!!! I love the tap water where I live. Buying water which I had to do when I lived abroad gets old fast. Plus I felt so guilty buying so many plastic bottles. Tap water is very much underrated.
Attitudes towards recycling and general environmentalism and being relatively green. In the other country I lived if I bought a single bar of chocolate like a twix the cashier would put it in a plastic bag... it was so annoying. Of course I always took it out and said "save our oceans" but really... very annoying.
Trust. We are a trusting nation. If I get in a taxi and need to stop at an atm to pay the fare, no problem. Do that in some countries and there's sheer panic and locking the doors thinking you're going to run away or something.
Politeness- people generally hold the door for the person behind them and say please and thank you, queue up etc.
Equality/tolerance/open attitudes... okay we're not perfect by a long shot. But some places still pay people different wages based on nationality. Arrest people for being homosexual. etc etc.
The live and let live attitude, and generally more introverted, quietness of our nature. Sitting on trains quietly etc. Whereas some nationalities love to squawk loudly on loudspeaker the whole journey. No, I don't wish to hear your conversation thanks!
The fact things are so easy... I know people moan about customer service but honestly, it is a dream to just be able to say can you fix the boiler and someone come and fix the boiler without ripping you off or not turning up or turning up a day early or not having the right equipment or coming and not having a clue but being too afraid to admit they don't have a clue...you get the point!
The fact we're allowed to criticise and moan about our governments shortcomings and hold them to account. (I do think our tabloids have gone way too far with the negativity and vitriol though).
Proximity to Mainland Europe and short flights so can get city breaks at long weekends etc
Countryside, I love the quaint countryside! The perfect little villages. Rabbits! Deer! Sheep! Cows!
The fact that in a thirty minute drive you are likely to be in a totally different town/city/village/forest/castle etc etc- I like at weekends being able to explore different places.
The cheap shops. Primark. Wilko. Poundland. I love being able to buy a new lightbulb or whatever I need and not having to pay the earth or barter for items.
National Insurance, state pension, NHS, free education.
Fish and chips by the seaside. Yum.
Family.