Visit your nearest National Trust Garden.
In all honesty, I've only actually been to a handful of National Trust gardens however it's free and such a lovely way to spend a few hours of your day. An added bonus is that you can bring your camera for some snaps of the flowers and your outfit in some beautiful backgrounds!
Play a game of tennis.
Doesn't matter if you've never picked up a racquet before or if you're the next Roger Federer, tennis is a good laugh for everyone and only costs a small amount to hire a tennis court for an afternoon.
Camping's always better in the sun so grab a tent, some marshmallows and a few friends and hit up a local campsite or a field for a chilled out night!
Try making ice cream.
Everyone loves ice cream so why not have a crack at making your own, it's not too hard and if you're not up for it then you can always make a trip down to the ice cream van instead!
Have a water fight.
Tuesday was the hottest day of the year so far so myself and a group of friends made use of it by having a massive water fight. I'm talking waterbombs, buckets and for whoever's quick enough, the hose! It's great fun and costs barely anything!