What would I do? Well first thing would be to get a couple of estate agents round to look at your house. Given that they would know the area and the current market value of what certain types of houses would be worth, etc. I would then ask them for their opinion, i.e. what would add more value, what would sell better, what in their opinion would they definitely NOT do, etc. etc.
Most estate agents are more than happy to do this. With that information, it would then give you a better steer on what might be worth looking at in more detail hopefully saving you time, effort and anguish in terms of building quotes etc.