If you are startng in the NW, note that the Atlantic coast Gulf Stream is a lot milder than the North Sea which is ffffreeezing all year round. I live on the E coast of England and the SW (Cornwall, Devon) gets spring a few weeks earlier but there are no guarentees as to when spring arrives.
Travel to London Heathrow may be cheaper than Amsterdam. You can use rail to get away from London. If you are smart it doesnt cost too much but a naive rail user can get stung. Its so much easier in the rest of Europe.
Youth Hostels are a useful option and should be pretty empty but some fill up for field trips during the Easter break. Many hostels are old country houses, castles or in premium locations.