Seeking advice about starting up my own business

I’m looking at starting a used car sales business in the UK and would appreciate some advice from anyone who’s been through it.
I’m already affiliated with BCA, so sourcing stock isn’t my main concern. What I’m trying to figure out is whether it makes more sense to start as a sole trader or set up a limited company from day one.
Initially, I’d be starting small with a handful of vehicles while testing the market and keeping overheads low. However, I do plan to grow the business if things go well.
For those who run or have run a car dealership business in the UK:
Did you start as a sole trader or limited company?
At what point did you switch (if you did)?
Were there any issues with trade insurance, finance, taxes, or dealer accounts when operating as a sole trader?
Looking back, what would you have done differently?
Any advice would be greatly appreciated.