Doon frae Troon
Ryder Cup Winner
If Scotland goes independent and joins the EU, so no longer independent ironically, then they will trade with the UK under the same terms as the rest of the EU nations. Countries are not allowed independent trade deals so if tariffs exist between the EU and the UK then they will exist between Scotland and the UK.
You need to stop referring to England. The UK is a combination of countries. I know that suits the story but it is inaccurate and misleading.
The UK is two countries, once Scotland leaves England will be the only country left.