Not a chance. During the war years the UK tried very hard to be self sufficient in food and fell well short. Population was significantly lower then as well. Agricultural yields are not that much higher now and less land is used for agriculture so without massive change of use of the land for more intensive agriculture and only having meat occasionally there is no chance of even getting close to self sufficiency in food.
Can’t speak for other agri sectors, but I can for wheat
Wheat(Hectares) 1940-673,984
Wheat(Hectares) 2000-1,956,759
UK wheat yields have more than trebled over the past 60 years from around 2.5 tonnes/ha in the mid-1940s to 8 tonnes/ha today.
World yield of wheat went from 1.0 tons/ha in 1940 to 3.0 in 2000