I think the trade-off is that we should be self-sufficient for essentials and should trade in luxuries.
Esssentials to me means:
- Electricity generation (not that we won't import if things go wrong, but we should have capacity for our peak load). This ideally means as much renewable generation as possible, obviously we do need to import uranium but we can take a very conservative approach to having enough!
- Water supply
- Basic food supply (i.e. we should grow enough staples like wheat and corn for domestic consumption, same with milk and butter etc, and the aim should be that most meat eaten in the UK is produced in the UK, as locally as possible as food miles are bad, same with other foods we can grow here e.g. apples). It's fine to import luxury foods, and of course to sell some of ours to other countries; the key is that if a war occurred that fully closed our borders (or for that matter a pandemic) for an indefinite period, we would not have a famine on our hands.
- Transport - roads and public transport (and I'm concerned about the reliance on Chinese EVs for bus services; get the wires up on busy routes and avoid the need for all that lithium, about which future wars will be fought).
- Healthcare provision (though for obvious reasons not medical supplies themselves, though we may want to licence UK production of as many "staple" medications as possible)
With regard to housing, it should not be legal for anyone who does not have British citizenship or indefinite leave to remain to own residential property in the UK either directly or indirectly (again extended to EU equivalents if we rejoin). I don't give a monkey's what happens to business property - that can be invested in if the Chinese etc like. Similarly a business which is directly or indirectly non-UK-owned should not be able to own residential property or its freehold in the UK. Such companies should be allowed to construct it but only on the condition of full sale to a UK owner. People who do not have the permanent right to live in the UK can rent property if they wish to have somewhere to live, and there's not enough UK residential property on the sales market for us to be in a position to allow outside investors to buy it for let.
These should either be nationalised, or be operated by companies which legally cannot be in overseas ownership, either directly or indirectly (other than EU companies if we rejoin).
The key is that it should be impossible for any other country to hold us at ransom for things we NEED.
We've been in that position before, there's no reason we could not be again. Plenty of other countries do have measures like these in place.