A few things regarding your setup:
1. Make sure you keep your heater pointing (especially if it is IR) away from any flammables as well as electronics (your computer!)
2. Make sure you completely unwind the heater's power cable (not kept in a loop) while you use it
3. The constant switching of the high powered device (heater in your case) may cause spikes or drops in the voltage on the line, which "may" cause issues with your PSU and therefore your PC. Those effects may be small and could be immediate or your PSU may not last as long. To avoid this situation it may be worthwhile into investing in a UPS to filter the power that is being supplied to your PC.
4. Depending on your financial capability and location of said socket in the room, it may be worthwhile in paying an electrician to come and install a proper power point anywhere else in the room that you like. It shouldn't cost much (maybe ~$200 total), it would make things safer (not running everything from one powerpoint) as well as giving you options for future decoration or moving furniture around (having power points in different places).
Good luck!