That all depends how it interacts with the various trade deals we need to get signed.Nonsense, if ever I heard it.
If you think ELMS is going to deliver as much as you suggest, then you totally misunderstand it's aims.
As @warksfarmer points out the £ is historically relatively weak right now, if it climbs much it could easily take £25-35/t off current wheat prices. Move to a net exporter and you're looking at another £15/t off the price, although ELMS and CS should reduce the chances of that going forward. Add a run off good world harvests into the mix and it could easily look very different quite soon. Or not. Maybe.