Your Home in The Gambia
Most volunteer accommodations are very basic, especially those that are upcountry. You will be lucky to have a western-style flushing toilet, and running water and electricity for a few hours a day (upcountry these three things barely even exist).
Housing can be situated in a compound where you will live right next door to Gambians or you could be on your own in an apartment.
As this is Africa, insects will likely find there way into your home, notably (large) spiders, cockroaches, ants, termites, flies, and mosquitoes.
Fortunately though, most homes have a resident gecko that you may catch a glimpse of at night and it will eat many of those unwanted critters. 
Just pretend you are camping for a while (with having dirty feet all the time, eating canned food, having very little electricity if at all, being without all the modernities such as a TV, and sleeping under a net).
Most volunteers, ex-pats and locals alike hire the services of a housecleaner. For example, you can have a woman come in and clean your house and do your laundry (washing, drying, and ironing) once a week for around D600/month plus food and transport (another D100 or so).
It is well worth having a housecleaner not only for your own convenience but also the social responsibility of employing someone local.
If you are living like most volunteers, the chances are that you will be taking "bucket" showers as you may be in an area that has frequent power (thus water) outages, the pressure of the water will not be enough for an actual shower, or you may not have running water at all and will be visiting the local well each day.
So, on those colder mornings and evenings during the winter months, heat up a kettle of water and add it to your buckets of water for a little bit of 'luxury'.
Mostly Cloudy 25 oC