Scotland, England, NI and Wales are indeed countries, but so is the UK. Again, look up the definition.
One main parliament for the whole country, with an MP elected for each constituency, so no democratic deficit. The second chamber really isn’t really a big deal.
There’s absolutely no barrier to stop working class people getting involved in politics. Neil Findlay was a brickie and he managed it, despite not going to Eton or having a nanny.