Break for me DH and DD15

[Kaz2200]

Looking for a short break for my daughter after finishing her gcse's, usually we take her older sister or a friend, but no one else can make it this year. I'm reluctant to take her on her own as she will be stuck with me and DH and I'm worried she'll just be bored and on her phone the whole time, but I do feel she could do with a break of some sort, fairly low budget, has anyone any ideas?

What does she like doing?

London?
Or another 'cool' city break - Berlin? Belfast and do the Game of Thrones tour?
Hard to recommend places without knowing what she likes doing!

Hmm, typical teenage girl, shopping, sunbathing, swimming, definitely not sightseeing, she is quite sociable so would love somewhere she could meet others her same age and hang out. We have narrowed time down to 4 nights in July, so would like a short flight, and short transfer to maximise out time.

I'm not sure a city break is what we are looking for, maybe something more relaxing.

Lanzarote?
Plenty to see on tours, nice beaches to go to, lovely sea front of restaurants (not over expensive) in Playa Blanca