Not a comprehensive list but the ones in BOLD are essential
Malarial Tablets
Insect repellent spray
Sun screen (factor 50)
A cap or hat
Long sleeved shirt for evenings
Long trousers for evenings
Mosquito net
Your personal medication if any. Enough for the whole trip and some spare (just in case)
Personal basic medical kit (there is a comprehensive HSE first aid box at each project)
Personal hygiene kit
Re-hydration sachets
Comfortable strong footwear
Sufficient day wear (washing is by hand, drying by sunlight)
Flip flops for use in washing areas
Torch/es and spare batteries. A head torch is useful
A power-bank for your phone and associated plugs and cables. SIM cards are available at reasonable cost and top ups available in most villages no matter how small.
Ghana plugs are the same as UK plugs
Sheet sleeping bag or similar (single duvet)
Pillow
towels
plates/mug/cutlery (just in case)
Thin blanket or opening sleeping bag (one or two season) useful for pre-dawn chill