Your loft is generally the warmest space in your home in the summer and the coldest in the winter and this is why thermal insulation is required under building regulations.
Things to consider
1. Add some form of heating when converting it. You could choose to extend your central heating, opt for underfloor heating or an electric radiator.
2. If you plan to extend your central heating, use a Gas Safe or HETAS engineer to check whether your existing boiler is powerful enough to heat the extra space. If it’s an older boiler or you’re adding an extra bathroom, it may just not have the capacity to cope.
3. Consider linking whichever heating option you choose to a smart device to help save you some money on your heating bills.
4. Make sure the loft is well ventilated.
5. Add as many windows as possible but install blinds or shutters to keep the heat out.