About half the immigrants are from outside the EU and the UK has always had full control over them.
Whilst *technically* true isn't *functionally* true. For every carrot picker we bring in from Poland we lose space for a high skill employee doing something of high economic value. It's just the reality of the world. Government needs to be seen to not be trying to replace the native population wholesale and to do that needs to curb immigration from outside the EU. Not to say everybody coming from the EU is low skilled but it's a more than significant proportion. Not to say that low skilled immigration isn't often useful - but there's absolutely no way to control it, and that isn't healthy when those people's costs and expectations of living standards are different to the native population's.
if you want to become totally dependent on imports for food - not something that sounds v sensible
Not *totally* but at the same time there's no reason or the UK to grow a lot of food that we do. We should stick to what we're good at and has value and import the rest. Get a bit of peace and prosperity going in Africa (I could talk about the effect the CAP has on the economy of Africa and why it causes the mass immigration and frankly civil war that everybody is tearing their hair out about in Europe without looking at the actual root cause of for days) by helping them grow things that grow well there, buying things that grow well in other places from there. The economics of this are well documented and known to the EU but they refuse, pointedly, to take action on it because they don't want French farmers spraying shit up the side of the EU buildings in Brussels, which is apparently a good excuse(?!).
Of course, you can import your strawberries from the Netherlands, but that's going to increase the cost to consumers.
We import strawberries from all over the world anyway, best I've had in recent years not from PYO were from California and Israel (not in the EU). Most UK grown strawberries are left for PYO, not a whole lot go to supermarket - the main bulk in supermarkets are from Spain and North Africa (Morocco et al - also not in the EU).
Also yes, fwiw, we absolutely shouldn't have a problem with importing food from other countries. We do it anyway so what's the point in haggling over percentages?