>>If so many important things are not up for the vote, is it really a democracy?

Exactly. For me, this is the myth of democracy. A party campaigns on a manifesto containing a few cherry-picked policies, aimed at appealing to enough of the electorate, to get them elected [quite often with less than 50% of the vote]

And, assuming they have an overall majority in parliament, this then means that every decision they subsequently make over the next 4 years is legitimised in advance because "you voted for this".

The only true democracy would involve regular referenda, whenever major new policies were proposed. This should be technically feasible with current technology. But, given the last time we had a referendum in UK the people didn't vote for the option they were meant to, I'm doubtful we'd ever see such a thing implemented.