https://www.rac.co.uk/drive/advice/know-how/driving-myths-your-questions-answered/
Although the RAC is not The Law its a good info piece
[i]”[b]1. Is it illegal to eat and drive?[/b]
No. It’s not illegal to eat and drive at the same time. However, if you present a significant danger while snacking on the move, the police could prosecute you for careless driving if they consider you not in proper control of the vehicle.
A study by Leeds University found that motorists who ate while driving were actually 44% slower than usual…
2. [b]Is it illegal to drink when driving?[/b]
Similar to eating, drinking at the wheel is not illegal, but it can carry the same careless driving penalty.
The same Leeds University study found that those who took a sip of drink at the wheel were 22% slower and 18% more likely to show erratic lane control.”[/i]