I am a software engineer from Pakistan with over 20 years of experience. I have a friend in the UK, who along with some partners, wants to create a startup. He has recommended me for building all the tech side of it. I have met with them online and now they want to meet me in person. They would eventually like for me to work in the UK on a work visa. They will be bearing all the travel and accommodation expenses. I am employed, married with children, and have property in Pakistan, so I am hoping I won't be refused on the grounds of "will leave the UK at the end of the visit" or "insufficient funds".
I was originally going to apply for a Business Visa with the intention of going for an interview. I would receive their invitation letter from another company that they have founded previously because they haven't registered the startup yet. However, that company doesn't have the license to recruit internationally from the Home Office and it would be too much of a hassle to get the license for that company. They would get that license for the startup once they register it, but that will take time.
So, one obvious objection on my visa would be that the company that is inviting me for the interview cannot really hire me because they don't have the international recruitment license. Now looking at the Business Visa requirements, my intention to visit doesn't fall into any other categories. Could anyone guide me as to which kind of Visa I should apply for?