Socksontheradiator
I'm assuming the list of products that will be tariff free is a random sample, but it did amuse me.Jams, jellies, spoons, television, onions and carpets.
Yes, a random sample - BBC humour? 
Havanananana
The present tariff on oranges from Spain is zero.The present tariff rate on onions from France is zero...
Yes, I know - but a lot of posters on this forum are under the impression that direct tariffs are being imposed on all imported fruit and veg - not for at least 12 months if the temporary tariff regime is adopted (it could be extended beyond 12 months.)
The shortages of foodstuffs pushing up the market price (Page 1 of any Supply and Demand textbook)
We don't know there will be any shortages of food yet - it's all supposition.
We don't know how the market will react - we do know that UK farmers are worried about cheaper imports, together with not being able to export their produce to EU countries - this would result in a surplus and cheaper prices. Will UK supermarkets, for example, put pressure on Spanish orange growers to lower their prices to cover non tariff barriers? How dependent are Spanish orange growers on the UK market? Will UK retailers/wholesalers source cheaper markets - Tunisian olives/olive oil for example?
"Too much of Tunisia’s quota of olive exports is as unfinished oil, leaving plenty of profit for European–mainly Italian–bottlers and marketing operations in a lucrative cartel." ... "Meanwhile, European consumers pay more than they should for groceries while sending big EU cheques to shore up Tunisia.Where’s the sense in that?"
www.cityam.com/thinking-smaller-why-tunisian-olives-hold-key-uks-post/
Profiteering on the part of wholesalers and retailers
I doubt it - not the big supermarkets/wholesalers.
Shortages of labour to pick, pack and process the UK produce resulting in shortages of supply.
There are shortages of labour every year - we may replace EU workers with cheaper, seasonal, non-EU workers in the short term. In the long term automated picking is on its way;
"Autonomous machine expected to pick more than 25,000 raspberries a day, outpacing human workers." "The robot has been developed in partnership with Hall Hunter, one of Britain’s main berry growers which supplies Tesco, Marks & Spencer and Waitrose."
www.theguardian.com/technology/2019/may/26/world-first-fruit-picking-robot-set-to-work-artificial-intelligence-farming
The increase in price of imported food due to the fall in the value of the £ against the € and $
Foreign exporters/UK wholesalers may absorb some/all of the cost - we don't know yet. We don't know what the exchange rate will be in 3 months time, what trade deals/EU deal we might arrange before the 31st October, what counter measures the Bank of England will take...