I currently only have 1 gallon demijohns for wine making, however I want
to start thinking about moving up to 5 gallon/25 litre quantities. I'm
undecided about what to age my wines in. I'm looking for something that
I can put on heavy duty shelving for a couple of years. I've had a good
search and the only containers I can find are plastic, oak or glass. Oak
sounds nice in theory, but sounds hard to look after and is quite
expensive to replace if things go wrong. I can also get oak tones with
beads/staves. Glass is something I'm thinking about and commonly
available. What other alternatives are there?

I've seen mentions of stainless steel, but can't find anywhere in the UK
that seems to sell kegs suitable for wine making. Does anyone know of a
retailer? There's lots of (expensive) beer stuff with pressure valves
and stuff, would they be usable? There several local metal workers who
could probably weld me something together. Does anyone know of any plans
I could use if I go this route?

Would storing in the plastic barrels most home brew shops for two years
or more be a problem?