My studio flat is tiny and lack of space. I am thinking to convert the loft space into a mezzanine level to make an extra bedroom space. It all sound good and I have permission from my leaseholder. But, it is far too expensive. The little flat only value as £46k and the conversion is going to cost £15k. Am i crazy to get this done? I need expert advise.

A bit late in replying, just saw your post now. If you will get the money back when you sell it then it is worth every penny. Ask an estate agents' opinion, anything that gives you extra space, is worth it!