Regarding weather and other aspects. The major problem is wind! At least in South England, I experienced many days with strong winds, which made it useless to spend £350 an hour on approaches and holds. Do your IR during Spring/Summer and you should be fine, do in Autumn winter, and can be tough days. When wind over 20 - 25kts at altitude, it is a waste of money to go up to train.
Fog, low clouds, depending where you training and what facilities they have at their local airfield.
Also you will be doing Cat 1 Single Pilot Ops., so for precision approach you must have 800 m Vis, for NON precision, you must also have cloud base above MDH!
Some exercises requires good weather, example unusual attitudes + flying visual approach with one engine.
Anyway good luck, you probably need £12.000 - £15.000 to be safe.