We are of course discussing this with a tax expert, but there are many different options and other subjective matters aside from tax. Taxation is tricky as many things are changing quite rapidly for founders thanks to Draghi's report. Where would you incorporate? Would you keep your operations in the same place? What are your favorite locations?
As a British person, I suggest you be careful with incorporating in the UK. It is in many respects an excellent location for entrepreneurship, but the new Labour government and Trump's re-election in the USA means that our relationship with the EU could go either way. If you absolutely need public money from the Commission to make the business work, there are 27 countries that don't have the imminent risk of that disappearing!
Which is a little different from the traditional system of spending everything you earn in R&D in order to not pay taxes, in Estonia this means that you can sit on it for a year or two as long as it stays in the company, and then re-invest it when proper opportunity present itself, that is not just re-investing for the sake of avoiding taxes like it happens in every other jurisdiction