"Get a lodger" started early in this thread!
I'm sorry, I know it's all relative, but £58k is a very high salary in most parts of the country.
You have a lifestyle problem rather than a salary /job problem.
Ah, the stuff I would do on £58k If was on my own with no partner or kids!
So, I get that the £58k has a few caveats attached to it, but it is ridiculous to assume that it is normal for a single person to struggle on your salary.
First thing I would do is sell the house and buy a nice one bedroom flat with a good sofa bed for visitors, or a not as nice two bedroom..downsize property by £50k or knock £500 off your mortage payments by moving. That's the main problem, you are living in a property that is clearly too expensive for you.
I bet you could get a cheaper car as well, knock another £50 off the monthly outgoings.
This should be a great time for you, there should be holidays and socialising on that money.
Time for big changes I reckon.