How different would British politics be if we had this Greek electoral rule? (Updated at 20:50)

I note in the Greek Parliamentary elections that the largest party, by however small that margin be, gets a bonus of 50 seats. In a parliamentary chamber of just 300 seats in total that means a 20% bonus for being the largest party. If the extra 50 seat rule had applied in the UK at the 2010 general election then the Conservatives would have had not 306 seats out of 650  but 356 out of 700, a small overall majority. If the rule had been a 20% bonus then the conservatives would have had 436 seats out of 780, a comfortable majority. In the former case the Conservatives could have chosen to operate as a small minority government, may be with some sort of support agreement with the Northern Irish Unionists, but at least without the dragging baggage of the Liberal Democrats. In the latter case the Conservatives would have had a comfortable majority and could have settled into a guaranteed five year mandate.

How different would the electoral scene have been if either of these scenarios had come to pass? Would David Cameron have enjoyed being a Conservative Prime Minister or do you think he actually enjoys being the head of a coalition and having the Liberal Democrats as his excuse for not governing as a Conservative but as a Liberal Conservative?

Update:
@badassday has tweeted a very fair point re 50 seat bonuses...