Planning a trip for April 2018

I would begin by reading Ricks travel book-Europe through the Back Door.

We travelled to Portugal end of April. It was sunny and warm and nearby Cascais was a nice beach town. Lisbon is a city that offers lots of interesting sites, lots of restaurants, good shopping and entertainment. Very friendly people as well. Easy to get to from London. Highly recommend Portugal for you and your daughter.

Am I correct that her spring break will be the first two weeks or the middle two weeks of April? This is when all the schools in Europe take their Easter holidays and therefore you will find that accommodation and particularly flights are more expensive. You may want to look at say Easyjet and put in your target travel dates to look for price spikes to see when to avoid if possible. I am going to Portugal in April, returning to London 19 April, a few days after the schools return and I paid £45, booked more than 6 months ago. Returning 4 days earlier, coinciding with the return of school children would have cost me more than £250.

Early April means that many places in Europe still won't be very warm. Portugal will be warmer than many places and Lisbon and Porto are a good combination for a week and you could then visit Dublin for say 3 or 4 days before heading to London.

I wouldn't visit Greece before the end of April if you want better weather. Southern Spain will be warmer. Berlin is one of the most interesting cities for modern history, but it won't be particularly warm in April.

If you want a higher probability of good weather, head to Morocco or the Canary Islands. The places you have previously visited are all larger cities - is this what you want for this visit?

You don't know where to begin? I would think the first place to begin is having a chat with your daughter. Verify she wants to visit a "warm" place too. She is 20 years old with her own ideas; see where yours and hers meet and start from there.