4seven: Arqiva B 12th stream
Food Network: Arqiva A
There is no mention of retuning in the Food Network Press Release, so it would imply that Food Network stays on Arqiva A. Also, being that close to the Olympics, it would surely fall within the Technical Lockdown period (note that the BBC has all their extra services ready on the EPG, plus the CBBC temp channel in Tyne Tees and Ulster, so that all they need to do is flick a switch - all the background tech work and LCN additions have been done ahead of the lockdown).
Big Deal (on air) incidentally is Arqiva B, TV News & Stars (both still off air) on Arqiva A.