Is there a website where I can gain some information on care of lemon
trees?

The one I have is hardy, but is situated in the conservatory. Although it
is thriving with new growth and some decent sized green lemons, I do get
some leaf curl and leaf drop. Is this normal?

Also, how much should I prune and when? Should I be ambitious with
pruning?

When do the lemons ripen in the UK, if at all?

I do give the tree winter and summer feed for citrus trees.