Don’t bother with LED’s for indoor light supplementation, Choose a 125w 6400k Blue spectrum Envirolight and suitable shade, you should be able to buy both for less than £50 and ideally you need to expose the plants to light for more than 12 hrs a day as otherwise you may trigger the natural flowering cycle but i guess 12hrs + of light a day may be inconvenient for you so try for at least 8 hrs of light a day and let the natural ambient background light do the rest.
envirogrolights info here
Blue (vegetive) 6400k spectrum light and reflecter here for £39.99
Another bonus of the light spectrum given off is that it staves off S.A.D syndrome when you are exposed to it.