There is not usually much need to work at height in fish and chip shops apart from:
Use of high-level storage on shelving etc.
Cleaning of ceilings, pipework, top of fridges and freezers etc.
Cleaning of windows
If you need to do these things you need to make sure you select appropriate equipment to do so.
Typically step ladders will be used, these are preferred to ladders as they are much more stable and can have appropriate handrails and guardrails to aid their use and to prevent falling. People working alone can use them.
However, Ladders should never be used without someone else who put their foot on the base of the ladder to make sure it doesn’t move. Even then ladders can still be dangerous if they are not put up at the right angle, or if you lean sideways or backwards when using them. Ladders should only be used for low risk, short duration tasks (less than 30 minutes).
If you are doing something that may take a long time, or is particularly high there are other things that can be used such as scaffolding or mobile elevated work platforms (MEWP/Cherry pickers)
There are a few main rules that should be adhered to:
Select appropriate equipment for working at height and make sure you check it is in good condition prior to use
Make sure the floor is level, firm and not slippery or wet
Ladders should be put at an angle of 75° (one unit out for every 4 up)
Be careful of any doorways that may open near where you are working and make sure everyone is aware you are working at height
When walking up a ladder or step ladder you should keep three points of contact, in other words keep two hands and one foot or one hand and two feet in contact at all times
Only light weights should be carried up a ladder, ideally under 10kg
Be careful with anything that you may drop onto people below