Help... Thinking about IHT, money for grandchildren etc. Any advice

My husband and I have agreed that we need to think about our finances IHT, giving money to gc etc)and haven't a clue where to start.I said we will try and gradually understand what to do. We will seek some professional help if necessary but even then I don't know how to find someone trustworthty and good. By looking at grandsnet just now it seems Trusts arent such a good idea. We have two adult chuldren, one of whom has two young children.
We thought of putting money into junior stocks and shares isas? Not sure them getting lots of money,if it mounts up, at 18 will be good for them. So any tips to do or not to do, or experiences,good and bad, you can share will be gratefully received, thanks