Joining in as a granny. I have 4 grandchildren, two in town and two living quite far away that i see a few times a year.
I did not have my mother nearby raising children, but did have my MIL who occasionally babysat, but never took them overnight. So I have a fair perspective for quite a few of you that have joined in this conversation.
Quite a few grandparents still work full time (I do), so a few hours on the weekend or during the week is a good portion of my off hours. I love to have my local GC over on a Sunday afternoon to hang out, allowing parents to do as they please. Occasionally a sleepover on a Sat night, but pick them up by noon - we are tired by then!
Remember too that a lot of grandparents also have living parents and are caregivers to them. Bringing Great-gran to shopping, doctors appts and visiting. We aren't call the sandwich generation for nothing.
Being a distance grandparent is heart-wrenching and hard for us as well. We miss them and want to be a part of their lives. We also don't want to be a nuisance, Face-timing at inconvenient hours. Try to work with them to let them know when is a good time to FT, so the kids get to know us and build a relationship. When we do visit, then the little ones can be comfortable while you take off for a long awaited date-night.
Also know that there are many distance grandparents that would really love to connect to little ones nearby. There are some organized groups (although I am not in the UK and don't know names) that can provide support and connection between generations. That woman at the grocery store or in the neighbourhood that stops to chat to your little ones might just be pining for a connection. Take notice of church or social groups, you just might make a new friend from another generation.
Hugs to all that miss having grandparents nearby 