A Broken System
"we'll end up with another prime minster that we didn't vote for."
Sorry to burst your bubble, but no prime minister has ever been elected. People vote for their local MP, not the prime minister or their party. Yes, its wrong, but that's the system we have. And, yes, it probably needs changing.
"To be honest, I think the only sure fire way to resolve this is to have another general election"
What, and keep calling elections until you get what you want? In any case, this may work against the Tories - the last three elections before this one had a very effective 'block the Tories' informal agreement between labour/libdem voters that could easily be revived, and the left leaning folk are a little rattled by this result, to say the least.
"Without a one party majority nothing will get done in terms of legislation and anything that does it through will be so watered down you might as well not have tried in the first place."
A few points regarding this:
1. We have had ~30 years of majority governments, and look where they got us (both labour *AND* Tory). Power corrupts, absolute power corrupts absolutely. It is not by accident that our politicians are corrupt (whatever their party). The reason we need PR is to spread that power thinner, so the corruption is less damaging. Ideally, we also need some form of direct democracy (i.e. a way of calling a referendum on any matter*) to take power away, too.
2. I would consider it a great benefit if less laws were passed, and more time spent considering them.
3. PR would allow us to take the best ideas of all parties instead of taking all the ideas of the least-worst party. We are selling ourselves very short here as all the parties (yes *all* of them) have had good ideas worth implementing.
"A lot of people have tactically voted and taking the popular vote at face value can be hugely erroneous."
Precisely. We need electoral reform so that we can properly express our opinions. The current system is badly broken for you and many, many others.
* There would need to be some exceptions, such as defence.