Where MPs come from

Who is currently allowed to become an MP? Who can navigate the circuit of putative parliamentary candidates in any of the parties? Only people already employed within the political process (mostly by MPs, or by the parties themselves and their semi-official thinktanks) could possibly secure the necessary paid, or even unpaid, time off. So, as things stand, only they, and people so rich that they do not need any sort of job at all, can ever become MPs.
This is another reason to introduce a system whereby each constituency party submitted a shortlist of two potential parliamentary candidates to a binding ballot of all registered electors in that constituency, and each party at national level submitted a shortlist of two potential Leaders (i.e., putative Prime Ministers) to a binding ballot of all registered electors throughout the United Kingdom. The first part of this would activley favour, in a way with a knock-on effect on the second part, people with real-world experience, and espcially such people who are already well-known locally.