As for the potential impact of Brexit,
"Under all Brexit scenarios modelled, prices of Fruit and Vegetables would increase, especially for those highly dependent on imports. "
Source: Imperial College London, study reported in New Scientist:
www.google.com/amp/s/www.newscientist.com/article/2192110-will-rising-food-costs-after-brexit-really-cause-thousands-of-deaths/amp/
"Brexit has the potential to have a substantial impact on the prices households pay for food. Currently around 30% of the value of food purchased by households in the UK is imported, and the major source of food imports is the EU. In comparison, only 17% of overall consumer spending is on imported goods. This means that changes in the costs of imports – for example, through changes to tariffs or movements in exchange rates – are likely to have a particularly big impact on food prices."
"These uncertainties over tariffs and the exchange rate mean that UK households are potentially going to be affected by considerable and unpredictable changes in food prices, with the poorest households much more exposed to this risk than the richest households. "
Source: IFS
www.ifs.org.uk/publications/9562
Mintec Brexit Food Price Index.
(Only shows actual current and past figures, ie during negotiation period and does not model for possible future figures (transition period and then Brexit period starting 01/01/21.)
"Methodology
The purpose of this Brexit food price index is to measure the changes in the price of selected food categories that are reportedly highly sensitive to the outcome of the Brexit process, particularly since the referendum in June 2016. The index will be updated and reported on a monthly basis.
Categories have been weighted based on the value of UK agri-food imports from the EU, with the fruit and vegetables category carrying the highest weighting, as the UK has a significant deficit in fruit and vegetable production.
The overall index (Chart 1) shows a spike after the referendum and has since been maintained at this high level. Various categories have driven the index at different points; however, the drivers have not been limited to Brexit, as discussed within the various categories below."
www.mintecglobal.com/blog/brexit-food-price-index