I'm playing with a batter now that we will use for a fish sandwich, and I was thinking I might play with it for fish and chips also. This produces a very nice crunchy coating. I'd probably use a good ale or perhaps a stout instead of the soda water. Anyway the recipe as listed works pretty well, I had to add a bit more instant mashed potato, but also make sure you wait till the IMP absorbs the moisture if you try it. First time I thought it was too loose (soupy), so I added more flour, then I had to adjust back again a bit later with more soda. Here's the link:
http://www.youtube.com/watch?v=0Mz4NTozNXw
Use only fresh fish, not frozen, as it really effects the texture, they tend to get mushy not flaky after freezing, and make sure the fish is at room temp and is dry. Not too thin a fillet either. I experiment using strips, so I can play with the batter and not make a ton of finished product while experimenting and adjusting.
for us its malt vinegar and coarse sea salt on both the fish and the chips
May not be a traditional beer batter, but makes one nice crunchy coating.
Oh yeah looked at my notes again, it works quite well with just the batter, or use fine bread crumbs instead of panko. For us the panko will flake off too much and create a oil issue, but for small batch home use should be ok any way.