I went along to the batting cages at Northwick Park on Saturday.
Though it can't replicate the conditions of a real game, it's pretty good fun. A token of 15 balls pitched from a machine costs £2 (I went for 75 - I was feeling greedy). The pitches vary somewhat; some were knee height, some nearer the shoulder, which you'd leave normally (unless you're me), but required an overhead smash to get away. Because there's meshing all around the cages, sometimes it's hard to tell how well you've hit it, unless it goes quite flat and far. Also, they're quite pedantic about helmets, even if you're playing slow pitch softball....it's really not in their interests for you to get injured though.
It's quite a trek to get to but worth it, I feel, if you need batting practice between games.