Hi Tanya.... and welcome to HT.
You will find answers to any questions in the Flight only/Airline and Airport section a few above this one. There's a special thread dedicated to hand luggage. Linda.

Hello Tanya and to H/T you can take food stuff crisps sweets chocolate that type of thing .when you check your bag in you can buy drinks (water coke )and take them on the filght with you ok .........colleen

It might be best if discussion is conducted in the HAND LUGGAGE Q&As topic which Linda refers to, as it is updated with any new changes to regulations. This topic may escape any updates, so it is probably best that I close it.

However, with regard to any drinks purchased after check-in, they would in fact have to be purchased airside after security checks. Any drinks purchased after check in but before security will be confiscated.

David