Thanks for all the advice so far. Really useful. I didn't know what a lintel was til I googled it after the posts above - pretty new to bigger DIY jobs (anything more than putting up shelves is big in my book!), so this forum is a great find now I've bought my first house.
Think I need to...
See picture... Had a lot of leaking through this bit of wall in bad weather. Old house and had dodgy gutters (now fixed). Started to chip away the plaster from a crack thinking could patch up easily, but came away and exposed wet and mouldy timber. I thought it was lath, but it's set into the...