You do have all my sympathies - my mum and I tarted up my gran's home to sell it (we needed as much cash as poss to pay for her care) and it was very emotional at times.
That's an awful push by the estate agent. Downright irresponsible, really. There's no way they should have taken photos like that - there are agents near here who will bring bloody bunches of flowers and shuffle the furniture to get good shots. I hate to say it, but it's very obvious from the photso even that the house has been left to itself while the family has other troubles, and I think that the buyer has realised this and is trying to take advantage of you. And to be honest, the photos are so awful that I can imagine some people imagining that the house was previously owned by a batty old lady with 25 cats who hoarded cash under her bed and who was finally dragged into a care home kicking and screaming.
I agree with Edam - at the least, you need an agent who'll say something like
"This spacious 4/5 bedroom family house, with a wealth of original features, is within 45 minutes commute of central Cardiff."
You also need to go back up there for a weekend, and at the least to get it sorted out so that you can do good photos - this may mean removing curtains / nets, taking up old carpet to expose floorboards, etc.
Have you had a chance to clean the house? We scrubbed granny's house all over, quite literally and it made a big difference.
But really, if you can, I'd agree with Fluffy, and that it's worth painting the house as well, taking the carpets up to show the floorboards and trying to stage it slightly with some spare, reasonably modern furniture. She's right on the garden, too. I think that awful thing is supposed to be a patio, but the weeds are so bad I genuinely can't tell. It looks like someone's doing the front hedge, so could they do the back garden as well? Pay a neighbour's teenager £6 to go and keep it under control once a week?
BTW, if not to your taste, you might be able to Ebay some of your grandad's furniture, you know - that 70s style is very fashionable with some people, and it's nicer that taking it to the skip.