An EHIC card gets you the same basic treatment as in your own country - but not the full treatment you'd get in the UK. The actual treatment you get in each country varies. The general rule is - you'll be charged to be seen by most doctors (other than a state hospital, which may be miles away). The EHIC waives the doctors consultation fee.
My wife was unwell in Portugal, and was seen immediately by the local doctor. He waived the �30 fee, but she had to pay �35 for medication. Our insurance had a �50 excess clause. Worth the doctors money, as she was much better the next day.
Each country is different. You need to check about traetment, just in case. Hopefully, you'll have a great time.