The winters in England can be wet and overcast. We may not see the sun for weeks at a time. I know, I live here.
However we can equally get weeks of sunny crisp days, just perfect for exploring.
In summer it may be cool and rainy or hot and sunny, sometimes both within a few hours of each other.
The best words to describe the english weather are variable and unpredictable (but with quite a bit more rain than mainland europe).
So when should you visit England?
The answer depends on what you want to see and do. A city break in London is pretty much the same regardless of the time of year. The only difference is that if you choose a open topped bus tour you might want to sit downstairs in Winter.
If you want to see the West Country (Cornwall, Devon, Somerset, Dorset) then spring is a great time to go.
If the rolling cotswolds with thatched cottages are more your thing, then high summer gives the best chance for fine weather and evenings spent in the beer garden of a traditional country pub.
Early Autumn is a great time to visit the hills of the Yorkshire Moors or the Lake District. If there is a warm snap, this is also a great time to visit the seaside as the water will be at its warmest.
Winter is great for long walks and visiting any of the hundreds of National Trust country houses. If you are a Downton Abbey fan and want to spend a week visiting similar ancient houses, well the budget tip is to join the National Trust. At the first house you visit they will try to sign you up. The cost is approximately the same as three visits to a National Trust property, but once you have signed up you can now visit as many NT properties as you fancy for 12 months (and there are many hundreds of properties to visit) and pay not a penny more either for entrance or for parking. Our NT membership cards are prised possessions.
So, in short, any time is a good time to visit England.