Hey @Account Closed
Nice to see someone from the UK here! Just for everyone’s benefit:
Flat = apartment or condo
BTL – Buy To Let, which just means a property you own that is being rented out (let = rent)
Now taking a stab at your question:
1) My suggestion is to stay conservative on your financing. If a deal only has strong cash flow figures because of an aggressive financing strategy, you need to pass on that deal and find one with stronger numbers (which I know is tough in UK but can be done). Keep in mind also, if I remember correctly, UK mortgages for the most part are fixed rate for only a 1-3 years, and then switch to variable. So you really want to be conservative with your financing over there because you don’t have the same 30 year fixed rate loans we do in the US, and there’s no promise rates will stay where they are now.
2) Generally, your idea that you can buy a house, improve the quality, and then refinance at the higher valuation and pulling out all of your equity (deposit + renovation costs) is correct. Biggerpockets calls it the BRRR strategy and you can find a ton of information here about it. It's going to be really tough to find a deal where the numbers work, but you just need to be persistent and a deal will come through.
3) You can if you like, but remember you are most likely going to lose all the favorable lending options available to someone who has a 9-5 job. Obviously speak with lenders, your CPA and lawyer, but its very common for folks to start out owning residences themselves vs corporate entities, and just having some sort of liability insurance.
If you do get an entity and what business credit, if I remember correctly you just need to register the entity with HMRC etc, and start out getting a credit card with whichever bank you choose to open a current account with. But again, have a CPA on hand to help.
Extra thoughts: I would have a think about getting a loan against your flat, even if its small like 20% LTV. Having a £350k flat with no debt is great, but taking out a small loan against it and reinvesting it in productive investments (like a rental) is not something I would consider risky.