1996 Peugeot 306 flashing rear and front lights after indicating left and opening the door

Car is old, but she drives fine in every way except that every if I am indicating right my break lights and headlights start flashing, and a loud ticking noise comes on, none of my stop lights do though.they also do this when the door is opening and just after closing even when engine is off. The garage repaired a faulty bulb in my left light headlight and took a look at all the earth switches and polished them, the say it's a possible electrical shortage somewhere else in the car, when the removed the rear right light there was quite a bit of water inside. They checked door seals and panels and there is no leaking in the car, she has 6 months mot and tax, does anyone have any idea what this could be and if so how much it will be to fix?? Wanna know if it is worth it for another 6 months or with to invest in something else now.