I feel like I'm going to faint after exposing myself to heat, please help me?

It's unusually hot in the UK today, like, hahaaha 15°C! I was sitting out in the April summer, not, and now i'm back in, I am very hot, feel dizzy, and I just feel generally faint. I just feel so tired and ill, and it's only 4pm! Anything I can do?

2015-04-18T08:10:21Z

Just realised I forgot some deatails:
I'm 15 and female, if that helps at all. thank you.

Amaretta2015-04-18T13:46:21Z

Drink plenty of water. You can cool yourself off by applying a wet cloth to the back of your neck.

Sylvia2015-04-18T08:21:25Z

heat stroke