Finnian is right a good dad is always with you.
When my Dad died last year my six year old said Grandad was safe in her heart, she worries about Mum who has AD and says she is "nowhere at the moment" but when she dies she will be safe in her heart with Grandad.
Children seem to get straight to the point sometimes.
Your Dad will always be real to your children if you talk to them about him, my husbands parents died over 20 years ago and all our daughters talk about them even though only our eldest has a memory of his Dad, his Mum died before any of them were born.
All my thoughts are with you.
Kathleen
xx