In new Brexit trade deals will we end up paying more or less for our imported goods and services?

There are arguments over how protectionist the current EU trade deals are outside the EU so that goods coming in from outside the EU are much more expensive than they need be. The EU say that the average tariff they put on in trade deals comes to between 2% and 3%. However a few goods like diary are heavily protected not just by the EU but generally by most countries.

It seems from EU tariff data that Brazilian potatoes have a 10% tariff while milk is a complex set of figures relating to fat content and organic or non-organic milk, sizes of containers and more. Some tariffs are not percentages but a cost in Euros per 100 kg. 

Does it matter if a few items have a high import tariff if the average is decently low?