I'll take Conservative/UKIP coalition over Labour/SNP any day. The idea that the SNP could have any sway over anything south of the boarder is appaling. Untill they're an all encompassing party with MPs south of the boarder they can stay up there. We really don't want to see people that hate the English ruling over the English.
And as for UKIP and conservatives. At least finally we'd get that referendum on the EU, which both Labour and Conservatives have promised in the past and not delivered.
As for the OP, i don't think it should be made compulsory. It's been made easier for people with the ability of postal voting. But
tbh, if people don't feel engaged by politics so that they don't want to vote for anyone, then they shouldn't have to.
Certainly more of an effort should be made to get young people engeged with politics, mabee MPs should go to schools and talk to kids about why it's important. But most parties are variations of a theme, it's like deciding between 2 sandwiches in a shop that are left that arn't one's you'd normally prefer.
The voting system won't change though, we had the vote on PR and it was rejected. We'll not likely see another effort to change things for a good few years. House of Lords reform is about the best your likely to see.