England/Scotland itinerary suggestions April 2019

As a first step, I highly recommend that you read a good guidebook such as the RS (I'm not affiliated with the RS organization) and look at some of the videos on this site. Two to three weeks is an adequate amount of time to see quite a lot in England and Scotland, but you still need to set priorities and decide what interests you the most. For example,

• Do you enjoy cities or do you prefer being out in the countryside and small towns?
  
• Are you fascinated by history -- and if so, what period(s) -- or do you prefer the modern world?
  
• Are you athletic (hiking, bicycling, kayaking, etc.) or do you just want to relax?
  
• Do you want to rent a car or rely on public transport?
  
• What budget level are you aiming for?

Be aware that the weather in April is likely to be chilly, but the days will be fairly long as it's after the spring equinox.

Sorry, but it’s too broad a question without more information.

Note that UK schools will be on their Easter break for the first three weeks of April, as Easter falls late next year, so places will be busier and more expensive around this time, so it’s good to be planning early.

Rick Steves guide to Great Britain is good.

If you plan to rent a car and drive this one is great:
https://www.amazon.com/Roads-Great-Britain-Eyewitness-Travel/dp/1465440259

Here is the travelogue of our four week drive tour of Wales and England
28 days in Britain and Celebrity Eclipse home
https://www.cruisecritic.com/memberreviews/memberreview.cfm?EntryID=599139

I think most people would really enjoy a day at Hadrian's Wall in the north of England.

Fly into Scotland and drive through on to England and end in London ;0..make it 3 weeks.. You won't regret it!

I'd recommend
5 days in Edinburgh
2 days in Alnwick
4 days in the Lake District
3 days in York
Dump your car take a train
6 days in London