Given the stance of the UK government, customs procedures likely will take longer and/or get more expensive next year.

It’s unlikely none of that cost will end up at consumers.

The UK has import duties. https://www.gov.uk/check-tariffs-1-january-2021

Which it could choose to zero rate if it stabilized food prices.

Which would have the knock-on effect of making EU food competitive in the UK but UK food non-competitive in the EU. Basically, making UK food industries less competitive.

That's before you get to WTO MFN which would mean we would have to reduce tariffs to zero not just for the EU but for the whole of the world, so our farmers would be competing against low wages everywhere. It would devastate our farmers in short order.

Yeah, I thought about this but I honestly don't know enough about how it works e.g. are countries allowed to bar food from coming into a country for not meeting safety standards even though they've set global tariffs to 0?

My gut says "yes" which is why I decided to shy away from that part.

Yes, those are the famous NTBs (non-tariff barriers). Since tariffs, apart from agriculture, are generally very low nowadays a lot of aim of free trade agreements is about reducing NTBs.

https://en.wikipedia.org/wiki/Non-tariff_barriers_to_trade

that would be against what brexit was voted for. the idea at least the one politicians were selling was that it would help improve local production by making EU products less competitive.