Grid it properly and if it is really South West facing i.e. your entrance is falling in South-West zone (S8 -W1), first you need to block it with appropriate coloured tape or metal strip according to zonal strength of the zone.
S8 Will lead you to disconnect from the rest of the world thereby severely affecting the financial position and again W1 will negatively affect the financial position and life span.
Since you have not mentioned department you would be looking or the core competency you would be dealing with, therefore right zone for you to sit in the office can not be advised.
Must read- Office Vastu Tips- Decoding the Mysteries for You