Can English people go to Greek Orthodox churches in England? I have been a non-churchgoing Christian now for a couple of years and have really taken Christian values to heart. I have so far learned how sinning was bringing me to a bad place and now I feel in love with humanity again. 

I decided I wanted to go to the Orthodox Christian Church but have been terrified of even speaking to them. I have lingering rejection issues from childhood.

The reason I like this Church is not only the Orthodox values, but I feel it would be interesting to worship with Greeks as I already know the alphabet and it might help me to get a fresh perspective on things.

Do Greek Orthodox churches in England welcome and accept English attendees?
First of all, please note that Greek Orthodoxy is one ethnicity/jurisdiction within Eastern Orthodoxy. Eastern Orthodox Christians speak many languages and there are generally Orthodox churches in the native language of many countries in the world.

So to answer your question: Yes.

The Greek Orthodox Church has even published the Divine Liturgy of St. John Chrysostom in English due to the increasing number of non-Greek-speaking people in the Church. 

For Eastern Orthodox churches in general, here's a list of English-speaking Orthodox churches in the UK. If you are only interested in Greek Orthodox churches, then check this out. Each Greek Orthodox church will have its own preferences on the language of the Divine Liturgy, with many being blended between English and other languages. You will need to visit to determine what each parish's practice/preferences are.