I am so happy. I had despaired of seeing it again, but the repairman did eventually respond to one of my many messages, and he did turn up - three days and 6 hours after the time he had promised to return it. He had it for just on 7 weeks in all, but all he did was clean it and replace the fan. He had done that when he rang me about it on Day 3, so for most of the tme he had it, the computer just sat on his bench. He said he decided it wasn't worth putting money into the computer as it was over 4 yrs old and unlikely to last long. I know there are massive gaps in my understanding of computers, but I had thought replacing the mother board (which is what he said he would do) was in fact updating the computer . Silly me! I was just so pleased to get my data back and, yes, I have now saved it all to an external source. I have plans now to upgrade the computer sooner rather than later - but I won't be ringing that computer repairnman to arrange it!.
To celebrate getting my data back, here's a pic I thought I had lost - it's the entrance to the Tower of London, taken last year in London. I won't bore you with the 3000 other pics which I could also have lost, but which are now saved!