Generally, it's OK and a good source of cheap stuff. I buy loads of things from there. The listing says if taxes are included if they are, which is now many of the items. If it says shipped from China and no mention of taxes, then you might get a bill when it arrives in the UK, but generally only if you paid something like more than £100. Small items, like controllers never get taxed. batteries often do, but not always.
Use Aliexpress if you can't get the item from Ebay. Often the Ebay price is the same, but taxes are already paid, so no hassle.