uk outdoor grow

hi there im new to this so here i go ive got 3 plant on the go at the mo growing outside with just soil and water and a bit of bat guano. The plants are now in there final pots where they will be staying till harvest problem is in the uk the weather can change quite a bit like 1 day were having lovely sun then we have 2 days with no sun will this affect the plants also they dont seem to be draining when i water them but the soil is drying out between watering????? ive had them since april and were now in july there about 3 feet now and just started to flower with two white hairs coming out from the nodes.any help would be good ill post some pics
cheers dave